Lectures on the history of physiology during the sixteenth, seventeenth, and eighteenth centuries

This is a digital copy of a book that was preserved for generations on library shelves before it was carefully scanned by Google as part of a project
to make the world's books discoverable online.

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject
to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books
are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover.

Marks, notations and other marginalia present in the original volume will appear in this file - a reminder of this book's long journey from the
publisher to a library and finally to you.

Usage guidelines

Google is proud to partner with libraries to digitize public domain materials and make them widely accessible. Public domain books belong to the
public and we are merely their custodians. Nevertheless, this work is expensive, so in order to keep providing this resource, we have taken steps to
prevent abuse by commercial parties, including placing technical restrictions on automated querying.

We also ask that you:

+ Make non-commercial use of the files We designed Google Book Search for use by individuals, and we request that you use these files for
personal, non-commercial purposes.

+ Refrain from automated querying Do not send automated queries of any sort to Google's system: If you are conducting research on machine
translation, optical character recognition or other areas where access to a large amount of text is helpful, please contact us. We encourage the
use of public domain materials for these purposes and may be able to help.

+ Maintain attribution The Google "watermark" you see on each file is essential for informing people about this project and helping them find
additional materials through Google Book Search. Please do not remove it.

+ Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. Do not assume that just
because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other
countries. Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of
any specific book is allowed. Please do not assume that a book's appearance in Google Book Search means it can be used in any manner
anywhere in the world. Copyright infringement liability can be quite severe.

About Google Book Search

Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers
discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web

at |http : //books . google . com/

Cambridge
Biological Serie

Lecturhs

ON THh

History of Physiologv

CAMBRIDGE BIOLOGICAL SERIES.

Gbnebal Editor: — Abthub E. Shipley, M.A.

FELLOW AND TUTOR OF CHRIST'S COLLEGE, CAMBRIDOE.

LECTUBES

ON THE

HISTORY OF PHYSIOLOGY

ANDREAS VESALIUS

BBUZELLENSIS, SCUOLAE MEDICOBUM FATAVINAE PROFESSOB

V (\y pTTVQ'

r^Lix> 1 ti \,LuH J

KO.R, Ml' y

ITmi Francis A. Countwn

of

CAMBIUDGB.

'rtl

ANDREAS VESALIUS

BRUZELLENSIS, SCUOLAE MEDICOBUM FATAVINAE PBOFESSOB

IhiUKi UF PHiS

EIGHTEENTH *

K.IJ.U., iLJ'.. .\LU., U.

TV»« Fran^t

A. CoMiitw«y

VT THE L

X 5 : 1 I * T r i * ■ I '

I»OI

LECTUEES

ON THE

HISTOEY OF PHYSIOLOGY

DURING

THE SIXTEENTH, SEVENTEENTH AND
EIGHTEENTH CENTURIES

BY

Sib M. foster, K.C.B., M.P., M.D., D.O.L., SecRS.,

PROFESSOR OF FHTSIOLOGY IN THE UNITERSITY OF CAHBRIDOE,
AND FELLOW OF TRINITY COLLEGE, CAUBRIDGE.

The Francto A. Countway
Ubrary of MedtebM

CAMBRIDGE:

AT THE UNIVERSITY PRESS.

1901

i.

iSDamtriDge:

PRINTBD BY J. AND C. P. CLAY,
AT THE UNIVERSITY PRESS.

TO

Db L. C. lane of SAN FRANCISCO

AND'

TO MY OTHER MANY FRIENDS OF THAT NEW WORLD,

THE STORY OF WHOSE LIFE IS AS YET

SO SHORT BUT MUST IN TIME BE SO GREAT,

I OFFER

AS A TOKEN OF MY FRIENDSHIP

THIS FRAGMENT OF THE STORY OF

THE OLD WORLD'S LIFE.

PEBFACB.

rpHE following Lectures were delivered as the "Lane
-^ Lectures" at the Cooper Medical College in San Fran-
cisco in the autumn of the past year. I have here and there
expanded some parts, but otherwise the Lectures now appear
very much as I delivered them. I do not pretend to have
given a complete history of physiology even within the period
to which I have limited myself I have chosen certain themes
which seemed to me important and striking, and I have striven
to develope these, leaving untold a great deal which might
be told concerning other themes. I have woven into the
story of ideas, the stories of the personal lives of the men
who gave birth to those ideas, partly in order to add to the
human interest of the tale, but also and even more so because,
in most cases at least, the fruitfulness of the labours of an
inquirer is largely dependent on the inquirer's character and
belongings.

I very much fear that I have allowed many mistakes in
what I have written to go unnoticed and uncorrected. I may
plead in excuse that historical research, perhaps above all other
kinds of research, demands ample leisure, and the time which
I have been able to give to the present little work has been
snatched from a life broken into bits by many and varied
duties. I shall be very thankful to have my mistakes
pointed out.

M. FOSTER.

Cambridge,

March 8, 1901.

CONTENTS.

Lecture Pages

I. Vesalius ; HIS Forerunners and Followers . . 1 — 24

II. Harvey and the Circulation of the Blood. The

Lacteals and Lymphatics 25 — 54

III. BORELLI AND THE INFLUENCE OF THE NeW PhYSICS . 55 — 83

IV. MaLPIGHI AND THE PHYSIOLOGY OF GlANDS AND

Tissues 84—120

V. Van Helmont and the Rise op Chemical Physi-

ology 121 — 144

VI. Sylvius and his Pupils. The Physiology of

Digestion in the Seventeenth Century . . 145—173

VII. The English School op the Seventeenth Century.

The Physiology op Respiration . . . 174 — 199

VIII. The Physiology of Digestion in the Eighteenth

Century 200—223

IX. The Rise of the Modern Doctrines of Respi-

ration. Black, Priestley, Lavoisier . , 224 — 254

X. The Older Doctrines of the Nervous System , 255—300

Chronological Table 301 — 302

Index 303—310

LECTURE I.

VESALIUS: HIS FORERUNNERS AND FOLLOWERS.

"* I MAKE no apology for having chosen as the subject of the
course of Lectures which you have honoured me by inviting me
to deliver, * The History of Physiology/ We are, all of us, even
in this farthest West, even in this closing year of the nineteenth
century, Children of our Fathers. Whaf we are is in ^part only^
of our own making, the greater part of ourselves has come down
to us from the past. | What we know and what we think is not
a new fountain gushing fresh from the barren rock of the
unknown at the stroke of the rod of our own intellect, it is a
stream which flows by us and through us, fed by the far-off
rivulets of long ago. As what we think and say to-day will
mingle with and shape the thoughts of men in the years to
come, so in the opinions and views which we are proud to hold
to-day, we may, by looking back, trace the influence of the
thoughts of those who have gone before. Tracking out how
new thoughts are linked to old ones, seeing how an error
cast into the stream of knowledge leaves a streak lasting
through many changes of the ways of man, noting the struggles
through which a truth now rising to the surface, now seemingly
lost in the depths, eventually swims triumphant on the flood
we may perhaps the better learn to appraise our present
knowledge, and the more rightly judge which of the thoughts
of to-day is on the direct line of progress, carrying the truth of
yesterday on to that of to-morrow, and which is a mere fragment f
of the hour, floating conspicuous on the surface now but '
destined soon to sink, and later to be wholly forgot.

F. L. 1

2 Vesaliits: [lect.

Nor need I, I trust, make any apology for having, though
invited to speak to medical hearers, chosen not the history of
medicine but the history of physiology. The whole story of
the rise and growth of the art of healing is too vast to be
gathered into one set of lectures, too varied to be treated of by
one man alone. I have chosen that part of the whole story
with which alone I am competent to deal; and I venture to
think that, without appearing to exalt unduly my own studies,
I may go so far as to say that a knowledge of the laws which
govern the phenomena of all living things is so essentially the
basis of all attempts to succour, or to watch over the welfare of,
one set of beings that the history of physiology cannot be
regarded in any other light than as the heart or kernel of the
history of medicine.

I do not propose to begin at the beginning of things. I will
leave on one side, for the present at least, the details of the
knowledge of the phenomena of life possessed by those whom
we speak of as * the ancients/ I will ask you to let me start
with the middle of the sixteenth century, and indeed with the
particular year 1543.

Those were stirring times, times of wars and rumours of
wars. The brilliant career of Charles V. was drawing towards
its close ; in that very year he was in the midst of his fourth,
his last and short war with his rival Francis I. of France.
Venice had still all the signs of outward splendour, but within
the rift in the lute was rapidly widening. The Medici were
once more established at Florence, and the burly Henry VIII.
was ruling over England. Some twenty years before Cortez
had conquered Mexico, some ten years before Pizarro had laid
hold first of Peru and then of Chili ; and Europe in the East
was enjoying the spoils of the West.

The times were times of strong under-currents of thought.
The Reformation was abroad. Luther was living his last years —
he died in 1546, the year after the Council of Trent — and
Calvin was strong at Geneva ; but the order of the Jesuits was
already a year old, and the Inquisition held Spain in its grip.
It was the heyday of Art. Though Raphael had been dead for
three and twenty years, Michael Angelo had nearly as many

i] His Forerunners and Followers. 3

yet to live, and Titian was in his prime. The new learning
was everywhere working like leaven ; the old Universities were
expanding and new ones were springing up everywhere, the
worth of the Greek tongue was preached by the learned ; and
the great exponent of the oldest of sciences, that of the heavens,
Nicolas Copernicus, closed his eyes in this very year. Moreover
learning was being spread as well as made ; printing had seen
its hundredth birthday and the presses of Venice and other
cities were pouring forth the means of knowledge. The night
of the middle ages had passed away in the dawn of modern
times. "' ^

In this year 1543 the printing-press of J. Oporinus (or Herbst)
in Basel gave to the world in a folio volume the Fahrica Humani
Corporis, the Structure of the Human Body, by Andreas
Vesalius. This marked an epoch in the history of Anatomy,
and so of Physiology and of Medicine. N Who was Andreas j^^
Vesalius, and why did his book mark an epoch ? /

Let me briefly answer the latter question first. In the ^ ,-
times of the Greeks mankind had made a fair start in the
quest of natural knowledge, both of things not alive and of
things living ; the search had been carried on into the second
century of the Christian Era when Galen expounded the
structure and the use of the parts of the body of man. As
Galen passed away inquiry, that is to say inquiry into natural
knowledge, stood still. For a thousand years or more the great
Christian Church was fulfilling its high mission by the aid of
authority ; but authority, as with the growth of the Church it
became more and more potent as an instrument of good,
became at the same time more and more potent as a steriliser
of original research in natural knowledge.

The Church held the gates of learning, and they who entered
were bidden to tread her path and hers alone. Her methods
became the methods of all scholars. Under her guidance the
written word took the place of the made world ; the pursuit of
truth ceased to be the looking into the phenomena of nature and
the seeking for the reason why; it narrowed itself to asking
what the teachers taught. The method which had proved
triumphant in the search after things spiritual was taken to

1—2

4 Vesalius : [lect.

be the method in all inquiry, and biologic inquiry was no
exception. As spiritual truths were learned by the study of
the revealed word, so anatomical and medical truths were to be
sought for, not by looking directly into the body of man, not by
observing and thinking over the phenomena of disease, but by
studying what had been revealed in the writings of Hippocrates
and Galen. As the Holy Scriptures were the Bible for all
men, so the works of the Greek and Latin writers became
the bible for the anatomist and the doctor. Truth and science
came to mean simply that which was written, and inquiry
became mere interpretation.

The *new birth' of the 15th and 16th centuries was in
essence a revolt against authority as the guide in knowledge ;
and the work of Andreas Vesalius of which I am speaking
marks an epoch, since by it the idol of authority in anatomical
science was shattered to pieces never to be put together again.
Vesalius described the structure of the human body such as he
found it to be by actual examination, by appealing to dissection,
by looking at things as they are. He dared not only to shew
how often Galen was wrong, but to insist that when Galen was
right he was to be followed, not because he had said it, but
because what he said was in accordance with what anyone who
took the pains to inquire could assure himself to be the real
state of things.

Vesalius like other great men had his forerunners. Long
before him at the close of the 13th and beginning of the
14th century Mundinus, Mondino (Raimondo de' Luzzi), one
of the teachers of the early days of the then great University
of Bologna, had dared to turn his eyes from the pages of
Galen to that of nature, and to learn for himself by actual
dissection how the body of man was built up. He learnt enough
to write a book of his own, the Anatomia Mundini, which
after him became a text-book in the schools, though used
perhaps more as an introduction or help to Galen than in any
other way. But Mundinus did not go far. He like other
anatomists, like indeed Vesalius himself, had to struggle against
not only the authority but the direct hand of the Church.
She taught the sacredness of the human corpse, and was ready

i] His Forerumiers and Followers. 5

to punish as a sacrilege the use of the anatomist's scalpel;
and what Mundinus did was done in the face of her powerful
opposition. For this reason apparently Mundinus had no
disciples carrying on his work ; all that remained of him was
his book, and he became little more than a smaller and a
later Galen.

Two centuries later, at the very beginning of the 16th
century, the power of the Church in its struggle against the
new light was lessening, and Jacobus Berengarius, often called
Carpi, from the place of his birth, a town in the state of
Modena, followed in Mundinus' steps with greater effect. He
asserts that he dissected no less than a hundred corpses, and
his teaching was undoubtedly to a large extent based on his
own direct observations.

He too however had his struggles with the Church ; he
was driven to desert Bologna where he had long taught, and
to live in retirement if not in exile at Ferrara. Nor did he
succeed in wholly reforming anatomical science, or in placing
anatomical inquiry on its only sound basis. For when he had
passed away the position of Master in Anatomical Science was
taken by a man of a different stamp, by Jacques Du Bois,
Jacobus Sylvius, a native of Amiens, who in 1531 began to teach
anatomy at Paris, and in 1550 succeeded Vidus Vidius in the
Chair of Medicine at the recently established College of France.

Sylvius, though in spite of his own attitude he added to
our knowledge of anatomy (we daily in the present time name
him when we speak of the fissure of Sylvius), was an un-
compromising Galenist. He tinisted Galen more than he did
his own eyes, and in everything taught or rather preached
Galen. Instruction in anatomy was to him reading a chapter
of Galen, and though he did make use of dissections, these
were used as mere concrete illustrations to render easy the
comprehension of what he was teaching, not as tests by which
the truth of what he was stating might be tried.

Sylvius, as we shall see, was Vesalius master, as indeed the
master of most anatomists of the age. His influence was at
the time of which we are speaking predominant ; with his help
the past efforts of Mundinus and of Carpi were brushed aside,

6 Vesalius: [lbct.

and Galen and authority reigned supreme in anatomical
teaching and thought. He was however the last of his school ;
his teaching was swept away by the new learning embodied in
the Fabrica Humani Corporis of Andreas Vesalius.

Who then was this Andreas Vesalius ?

He was bom at Brussels at midnight as the last day of 1514
was passing into the first of 1616. His family, which had dwelt
for several generations at Nymwegen and which originally bore
the name of Witing, bad produced many doctors and learned
men, and his father was apothecary to Charles V. His mother,
to judge by her maiden name, Isabella Crabbe, was probably of
English extraction.

The young Vesalius (or Wesalius, for so it was sometimes
spelt) was sent to school at Louvain and afterwards entered
the University there, which then as later was of great renown.
Though he diligently pursued the ordinary classical and
rhetorical studies of the place, the bent of his mind early
shewed itself; while yet a boy he began to dissect such
animals as he could lay his hands on. Such a boy could
not do otherwise than study medicine, and in 1533, a lad
of seventeen or eighteen, he went to Paris to sit at the feet of
Sylvius, then rising into fame.

The ardent young Belgian was however no docile heaier,
receiving open mouthed whatever fell from the master. Sylvius'
teaching was as I have said in the main the reading in public
of Galen. From time to time however the body of a dog or at
rarer intervals the corpse of some patient was brought into the
lecture room, and barber servants dissected in a rough, clumsy
way and exposed to the view of the student the structures which
the learned doctor, who himself disdained such menial, loathsome
work, bid them shew. This did not satisfy Vesalius. At the
third dissection at which he was present he, already well versed
in the anatomy of the dog, irritated beyond control at the rude
handling of the ignorant barbers, pushing them on one side,
completed the dissection in the way he knew it ought to be
done.

"My study of anatomy," says he, "would never have succeeded
" had I when working at medicine at Paris been willing that

i] Hi8 Forerunners and Followers. 7

" the viscera should be merely shewn to me and to my fellow
" students at one or another public dissection by wholly un-
" skilled barbers, and that in the most superficial way. I had
" to put my own hand to the business." —

Besides listening to Sylvius, he was a pupil of Johannes
Guinterius (Gunther), a Swiss from Andemach, who also was
teaching anatomy and surgery at Paris at the time, and
with whom his relations seem to have been closer than with
Sylviua

Neither Sylvius, however, nor Guinterius, nor any one at
the time was able to supply Vesalius with that for which he
was obviously longing, the opportunity of dissecting thoroughly
the human body. Complete dissection was then well-nigh
impossible, the m6st that could be gained was the hurried
examination of some parts of the body of a patient who had
succumbed to disease. One part of the human body, the
foundation of all other parts, the skeleton, could however be
freely used for study. In those rude times burial was rough .
and incomplete, and in the cemeteries bones lay scattered about
uncovered. In the burial-ground attached to the church of
the Innocents at Paris Vesalius spent many hours, studying
the bones ; and he also tells us how in another burial-ground,
on what is now *Les Buttes Chaumont,' he and a fellow
student nearly left their own bones, being on one occasion
attacked and in great risk of being devoured by savage, hungry
dogs who too had come there in search of bones. By such a
rough, perilous study Vesalius laid the foundation of his great
work, a full and exact knowledge of the human skeleton. He
tells us how he and a fellow student were wont to try their
knowledge by a test which has been often used since, the
recognition of the individual bones by touch alone, with the
eyes shut.

After three years the wars drove him back from Paris to
Louvain, where he continued to pursue his anatomical studies
with unflagging zeal. Here as at Paris he was driven to use
strange means to gain the material for his studies. Walking
one day with a friend in the outskirts of the city and coming to
the public gibbet, where " to the great convenience of the

8 Vesalkts : [lect.

" studious, the bodies of those condemned to death were exposed
" to public view," they came upon a corpse " which had proved
" such a sweet morsel to the birds that they had most thoroughly
" cleaned it, leaving only the bones and ligaments." With his
friend's help he climbed up the gallows and attempted to carry
off the skeleton, but in the hurry of such a theft in open
daylight he only succeeded in getting part of it ; accordingly
that evening he got himself shut out of the city gates, secured
in the quiet of night the rest of the skeleton, and returning
home by a roundabout way and re-entering the city by a
different gate, safely carried it in.

In 1537, after a year's stay at Louvain where, in the Februarj^
of that year, he put forth his first juvenile effort, a translation
of the ninth book of Rhazes, he migrated to Venice, the enlight-
ened if despotic government of which was in all possible ways
fostering the arts and sciences, and striving to develope in
the dependent city of Padua a University which should
worthily push on the new learning. /It may be worth while
to note, as an instance of how in the web of man's history
threads of unlike kind are made to cross, that among the monks
who had charge of the Hospital at Venice, at which Vesalius
pursued his medical studies, was one who bore the name of
Ignatius Loyola. We may well imagine that these two young
men crossed each other's path in the hospital wards or grounds,
perhaps even conversed with one another. One was gathering in
a rich harvest of exact knowledge which six years later he was
to embody and give to the world in a great book, the beginning
of modern biologic science. The other was busy with a scheme
for the spiritual welfare of mankind which six years later took
shape as the Order of the Jesuits. The one with his eyes fixed
on man's body brought forth a work, the fruits of which have
profoundly influenced and are still profoundly influencing men's
minds. The other, with his eyes fixed only on truth and
goodness, began that which after him became the incarnation
of Authority, an engine powerful it is true for good, but often
used for the support of lies and for the maintenance of evil.
No two things have fought and are fighting each other more
bitterly than the things which have sprung from the two

i] His Foretnmners and Followei^s. 9

works of the two young men who crossed each other's path at
Venice in the year of our Lord 1537.

The brilliant talents of the young Belgian at once attracted
the notice of the far-sighted rulers of Venice. He was in
December of that same year, 1537, made Doctor of Medicine in
their University of Padua, was immediately entrusted with the
duty of conducting public dissections, and either then or very
shortly afterwards, though he was but a lad of some one or two
and twenty summers, was placed in a chair of Surgery wdth care
of Anatomy.

He at once began to teach anatomy in his own new way.
Not to unskilled ignorant barbers would he entrust the task of
laying bare before the students the secrets of the human frame;
his own hand, and his own hand alone, was cunning enough to
track out the pattern of structures which day by day were
becoming more and more clear to him. Following venerated
customs he began his academic labours by 'reading' Galen, as
others had done before him, using his dissections to illustrate
what Galen had said. But time after time the body on the
table said plainly something different from that which Galen
had written.

He tried to do what others had done before him, he tried to
believe Galen rather than his own eyes, but his eyes were too
strong for him ; and in the end he cast Galen and his writings
to the winds and taught only what he himself had seen and
what he could make his students see too.

Thus he brought into anatomy the new spirit of the time,
and the men of the time, the young men of the time answered
to the new voice. Students flocked to his lectures, his hearers
amounted it is said to some five hundred, and an enlightened
Senate recognized his worth by repeatedly raising his emolu-
ments.

Such a mode of teaching laid a strain on the getting of the
material for teaching. Vesalius was unwearied in his search
for subjects to dissect. He begged all the doctors to allow him
to examine the bodies of their fatal cases. He ingratiated
himself with the judges, so that when a criminal was con-
demned to death they gave directions that the sentence should

10 Vesaliits: [lbct.

be carried out at such a time, and the execution should be
conducted now in this manner, now in that as might best meet
the needs of Vesalius' public dissections. Nor did he shrink
apparently from robbing the grave, for he relates how, learning
of the death and hurried burial of the concubine of a monk, he
got possession of the body, and proceeded at once to remove the
whole of the skin in order that the peccant holy man, who had
got wind of the matter, might be unable to recognize his lost
love. And he made dissections in Bologna as well as Padua.

Far away from the papal throne, in distant Spain, the
Church was all powerful, and there desecration of the corpse
with the knife was well-nigh impossible. In Belgium too and
in France opportunities for dissection were rare. But here, in
Venice, nearer the papal seat, the Church's hand was less heavy.
The high-spirited citizens of the Republic were resisting as we
know in many ways the Pope's demands; and under the
protection of the Senate, Vesalius had opportunities for the
advance of knowledge which he could not have enjoyed else-
where.
^" Five years he 0tra\ spent in untiring labours at Padua.
j Five years he wrougEfTnot weaving a web of fancied thought,
1 but patiently disentangling the pattern of the texture of the
\ human body, trusting to the words of no master, admitting
nothing but that which he himself had seen ; and at the end of
the five years/ in 1542, while he was as yet not 28 years of age,
. ' he was able to write the dedication to Charles V. of a folio
work, entitled the * Structure of the Human Body,' adorned
G[ with many plates and woodcuts, which appeared at Basel in the
following year^ 1543^ He had in 1538 published, under the
' sanction of the Senate of Venice, Anatomical Tables, and in
the same or succeeding year had brought forth an edition of
Guinterius, a treatise on blood-letting, and an edition of Galen.
There is a legend that the pictures in the great work were by
the hand of Titian, but there seems no doubt that they, like
the Tables, were done by one John Stephen Calcar, a country-
man of Vesalius.

This book is the beginning not only of modern anatomy
but of modern physiology.

i] Hi8 Forerunners and Followers. 11

We cannot it is true point to any great physiological
discovery as Vesalius' own special handiwork, but in a sense
he was the author of discoveries which were made after him.
He set before himself a great task, that of placing the study of
human anatomy on a sound basis, on the basis of direct, patient,
exact observation. And he accomplished it. Galen had at- ^
tempted the same thing before him ; but the times were not . -^
then ripe for such a step. Authority laid its heavy hand on
inquiry, and Galen's teaching instead of being an example and
an encouragement for further research, was, as we have said, made
into a bible, and interpretation was substituted for investigation.
Vesalius, inspired by the spirit of the new learning, did his work
in such a way as to impress upon his age the value not only of \
the results at which he arrived, but also and even jnore.srMif-ili^ ^
method by which he had gained them. He taught in such a
way that his disciples, even when they thought him greater
than Galen, never made a second Galen of him ; they recognized
that they were most truly following his teaching as a whole
when they appealed to observation to shew that in this or that
particular point his teaching was wrong. After him back-
sliding became impossible ; from the date of the issue of his
work onward, anatomy pursued an unbroken, straightforward
course, being made successively fuller and truer by the labours
of those who came after.

Vesalius' great work is a work of anatomy, not of physiology.
Though to almost every description of structure there are added
observations on the use and functions of the structures described,
and though at the end of the work there is a short special
chapter on what we now call experimental physiology, the book
is in the main a book of anatomy, the physiology is incidental,
occasional, and indeed halting. Nor is the reason far to seek.
Vesalius had a great and difficult task before him. He had
to convince the world that the only true way to study the
phenomena of the living body was, not to ask what Galen had
said, but to see for one self with one's own eyes how things
really were. And not only was a sound and accurate know-
ledge of the facts of structure a necessary prelude to any sound
conclusions concerning function, but also the former was the

14 Vesalius: [lbct.

" uses it for the cooliDg of the innate heat, for the nourishment
" of its substance and for the preparation of the vital spirits,
" elaborating and refining this air so that it together with the
"blood which soaks plentifully through the septum from the
"right ventricle into the left may be assigned to the great
" artery (the aorta) and so to the whole body."

And again,

"The septum of the ventricles, composed as I have said
" of the thickest substance of the heart, abounds on both sides
" with little pits impressed in it. Of these pits, none, so far at
"least as can be perceived by the senses, penetrate through
" from the right into the left ventricle, so that we are driven to
" wonder at the handiwork of the Almighty, by means of which
" the blood sweats from the right into the left ventricle through
"passages which escape human vision."

Even in this which he ventured to print the sarcastic note
of scepticism makes itself heard ; but what he really thought
he did not dare to put forward. He tells us in a later writing
that " he accommodated his statements to the dogmas of Galen "
not because he thought that " these were in all cases consonant
" with truth but because in such a new great work he hesitated
" to lay down his own opinions, and did not dare to swerve a
" nail's breadth from the doctrines of the Prince of Medicine."

That physiological problems were before his mind, that he
had thought over, and indeed had tried to solve them by
experimental methods, is shewn in the brief chapter, ' Some
Remarks on the Vivisection of Animals,' which is the last
chapter in his great work. In this he relates his experiments
on muscle and nerve, shewing that that which passes along a
nerve in order to bring about movement passes by the substance
and not by the sheath of the nerves. He tells us that it is
through the spinal cord that the brain acts on the trunk and
limbs, that an animal can live after its spleen has been
removed, that the lungs shrink when the chest is punctured,
that the voice is lost when the recurrent laryngeal nerve is cut,
that by artificial respiration an animal can be kept alive though
its chest is laid wholly bare, and that under these circumstances

i] His Forerunners and Followers. 15

a heart which has almost stopped beating may be revived by
the timely use of the bellows; and he tells us many other
things.

Obviously his vigorous and active young mind was starting
many inquiries of a purely physiological kind, and he was
aware that much of the physiology which he had put into his
book would not stand the test of future research. He knew
more particularly that the chapter in that book in which he
treated of the use of the heart and its parts was as he says
* full of paradoxes/ But he was no less aware that his bold
attempt to expound the plain visible facts of anatomy such as
they appeared to one who had torn from his eyes the bandages
of authority, was of itself enough to raise a storm of opposition ;
he feared to jeopardize his success in that great eflfort by taking
upon himself further burdens.

Experience shewed that in this he was right. Even while
he was writing his book, timorous friends urged hirp not to
publish it ; its appearance they said would destroy his prospects
in life. And in one sense it did. Towards the end of 1542
after the completion of his great task, although in August
of that year he had been reappointed to the Chair of Surgery
and Anatomy for three years, he, with the sanction of the
Senate^ left Padua for a while, his pupil Realdus Columbus
being appointed his deputy. He made a short stay at Venice ;
he visited Basel either once or twice, chiefly it would seem to
confer with his printers; but while in that city he prepared
with his own hands from the body of an executed criminal a
complete skeleton which is still religiously preserved there. He
also probably made a hurried journey to the Netherland^s.
During his absence from Padua, after the appearance of his
book the storm broke out. The great Sylvius and others
thundered against him, reviling him in a free flow of adjectives.
Coming back to Padua, after about a year's absence, he found
opposition to his new views strong even there, not the least active
among his opponents being his old pupil Columbus. He gave
lectures at Padua, oflfering to test publicly in the dissecting
theatre whether his statements were wrong or no. He lectured
also at Bologna, and at Pisa, where the enlightened Cosimo de'

16 Vesaliiis: [lect.

Medici of Florence would willingly have detained him as professor
in the University which he was nursing. But such tokens of
encouragement and others like them weighed before him little
when compared with the bigoted opposition of so many of his
brethren. The spirit shewn by the latter entered like iron into
his soul. If the work on which he had laboured so long and
which he felt to be so full of promise met with such a reception,
why should he continue to labour? Why should he go on
casting his pearls before swine ? He had by him manuscripts
of various kinds, the embodiment of observations and thoughts
not included in the Fahrica. What they were we can only
guess ; what the world lost in their loss we shall never know.
In a fit of passion he burnt them all, and the Emperor
Charles V., offering him the post of Court Physician, he shook
from his feet in 1544 the dust of the city in whose University he
had done so much, and still a youth who had not yet attained
the thirties ended a career of science so gloriously begun.

Ended a career ; for though in the years which followed he
from time to time produced something, and in 1555 brought
out a new edition of his Fahrica, differing chiefly from the first
one, so far as the circulation of the blood is concerned, in its
bolder enunciation of his doubts about the Galenic doctrines
touching the heart, he made no further solid addition to the
advancement of knowledge. Henceforward his life was that
of a Court Physician much sought after and much esteemed,
a life lucrative and honourable and in many ways useful,
but not a life conducive to original inquiry and thought.
The change was a great and a strange one. At Padua he had
lived amid dissections ; not content with the public dissections
in the theatre, he took parts at least of corpses to his own
lodgings and continued his labours there. No wonder that he
makes in his Fahrica some biting remarks to the effect that he
who espouses science must not marry a wife, he cannot be true
to both. A year after his arrival at the Court he sealed his
divorce from science by marrying a wife; no more dissections
at home, no more dissections indeed at all, at most some few
post-mortem examinations of patients whose lives his skill
had failed to save. Henceforward his days were to be spent in

i] His Forerunners and Followers. 17

courtly duties, in soothing the temporary ailments, the repeated
gouty attacks of his imperial master, in healing the maladies of
the nobles and others round the throne, and doubtless in giving
advice to more humble folk, who were from time to time allowed
to seek his aid. Whither his master went, he went too, and we
may well imagine that in leisure moments he entertained the
Emperor and the Court with his intellectual talk, telling them
some of the fairy tales of that realm of science which he had left,
and of the later achievements of which news came to him,
scantily, fitfully and from afar.

When in 1556 Charles withdrew from the world and took
refuge in the cloister, Vesalius transferred to the sod Philip II.
the services which he had paid to the father, and in 1559 returned
with him to Spain.

Spain, as it then was, could be no home for a man of
science. The hand of the Church was heavy on the land ;
the dagger of the Inquisition was stabbing at all mental life,
and its torch was a sterilizing flame sweeping over all in-
tellectual activity. The pursuit of natural knowledge had
become a crime, and to search with the scalpel into the secrets
of the body of man was accounted sacrilege. It was for a life
in priest-ridden, ignorant, superstitious Madrid that Vesalius
had forsaken the freedom of the Venetian Republic and the
bright academic circles of Padua ; in Madrid, where as he himself
has said, "he could not lay his band on so much as a dried skull,
" much less have the chance of making a dissection." Moreover,
he must have felt the loss of Charles, who, whatever his faults,
recognized the worth of intellectual^reflforts, and in many ways
had shewn his sjrmpathy with V^alius* love of knowledge.
Such sympathy could not be looked for in the narrow and
bigoted Philip.

We cannot wonder that amid such surroundings the feelings
that the past years had been years of a wasted life grew strong'
upon him, and that wistful memories of the earlier happy tydes
gathered head. He was still in the prime of life, a man of Bome
forty-five summers; many years of intellectual vigour were
perhaps still before him. Was he to spend all these in marking
time to the music of an Imperial Court ?

F. L. 2

>

18 Vesalitis: [lect.

Just at this time, in 1561, there came into his hands the
anatomical observations of Falloppius (Gabrielo Falloppio), a
man of whom I shall presently have to speak, who in 1551 had
after a brief interval succeeded Vesalius in the chair at Padua.
This book came to the wearied and despondent Vesalius,
banished to the intellectual desert of Madrid, as a living voice
from a bright world outside. " Putting everything else on one
"side, he gave himself," as he says, "wholly up to the instant
" greedy reading of the pages " which brought vividly back to
him the delights of his youth. Calling back from the past the
memory of things observed long ago, for new observations, as
we have seen, were out of his power, he put together bit by
bit some notes criticising Falloppius' work, put them together
hurriedly and rapidly, in order that Tiepolo, the Venetian
ambassador, then at Madrid but about to return to Venice,
might carry the manuscript with him. In that 'Examen,'
as he calls it, Vesalius says how the reading of Falloppius*
notes had raised in him ** a glad and joyful memory of that
" most delightful life which, teaching anatomy, I passed in Italy,
"the true nurse of intellects." He looks forward, he says, "to
" see the ornaments of our science continue to bud forth in the
" school from which I was while yet a youngster dragged away
" to the dull routine of medical practice and to the worries of
" continual journeys. I look forward to the accomplishment of
" that great work for which, to the best of my powers so far as
** my youth and my then judgment allowed, I laid foundations,
" such that I need not be ashamed of them."

And even more, he was nursing the idea that his present
barren life might be exchanged for a more fruitful one. "I
" still," says he, "live in hope that at some time or other, by some
" good fortune I may once more be able to study that true bible,
" as we count it, of the human body and of the nature of man."
He was still the Vesalius of old, unchanged by all the ex-
periences of a life at Court. The words 'that true bible'
epitomize his life's works. The true bible to read is nature
itself, things as they are, not the printed pages of Galen or
another ; science comes by observation, not by authority. And
we may perhaps go so far as to suppose that by adding the

i] His Forerunners and Followers, 19

words the nature of man, 'man himself/ to the words *the
body of man/ he was looking forward to doing in his riper
years for physiology what in his youth he had done for
anatomy.

But it was not to be. In 1563 he suddenly determined to
make a pilgrimage to Jerusalem. There are various legends
as to the reasons which led him to this step. It is said that in
making what was supposed to be a post-mortem examination
on a noble man, or according to others a woman suffering from
some obscure disease, it turned out that the body was still
living, and that the Church insisted upon the pilgrimage as an
expiation for an act deemed to be a sacrilege. The truer account
is probably that told by the botanist Clusius, that Vesalius, ill
in body, and we may add even more sick at heart, wearied of
the Court, and harassed by the Church, seized an opportunity,
and made the proposed pilgrimage an excuse for bringing to an
end his then mode of life.

On his way to Jerusalem he stopped at Venice and renewed
his intercourse with scientific friends. He there learnt that
the manuscript on Fallopius had never reached "that anatomist,
who had somewhat suddenly died in 1562, but was still in
Tiepolo's hands. His friends at once obtained it from Tiepolo,
and it saw the light in the following May.

The Senate at Venice were just then at a loss for a fit
successor to Falloppius, and it is possible that Vesalius during
his stay in the city made known his willingness to desert the
Court and to return to academic life; for it is said, though
documentary evidence is lacking, that during his eastern
journey he received an invitation to occupy his old chaii\
Alas, on his way back in 1564 he was taken ill, or possibly
a latent malady openly developed itself, he was put ashore on
the island of Zante, and there he passed away.

The influence of Vesalius on the history of science may be A
regarded on the one hand in its general, on the other in its
more special aspect.

Taking the general aspect first we may say that he founded
modem anatomy. He insisted upon, and through his early
unwearied labours by his conspicuous example he ensured the

2^2

20 Vesalius: [leot.

success of the new method of inquiry, the method of observa-
tion as against interpretation; he overthrew authority and
raised up experience, he put the book of nature, the true book,
in place of the book of Galen, and thus made free and open the
paths of inquiry^ Others before him, as we have said, Mundinus
to wit and Carpi, had made like efforts, but theirs were partial
and unsuccessful; Vesalius' efforts were great, complete, and
successful. Upon the publication of the Fabrica, the pall of
* authority' was once and for ever removed. Vesalius' results
were impugned, and indeed were corrected by his compeers and
his followers; but they were impugned and corrected by the
method which he had introduced. Inquirers asserted that in
this or that point Galen was right and Vesalius was wrong, but
they no longer appealed to the authority of Galen as deciding
the question, they appealed now to the actual things as the
judge between the two, as the judge of Galen as of others.
And even those who were Vesalius' most devoted disciples
never made of him a second Galen; they never appealed to
him as an authority, they were content to shew on the actual
body that what he had said was right.

XTnder a more special aspect he may be regarded as the
founder of physiology as well as of anatomy in as much as he
was the distinct forerunner of Harvey. For Harvey's great
exposition of the circulation of the blood did, as we shall see,
for physiology what Vesalius' Fdbrica did for anatomy ; it first
rendered true progress possible. And Harvey's great work was
the direct outcome of Vesalius' teaching, the direct outcome
and yet one reached by successive steps, steps taken by men of
the Italian school, of which Vesalius was the founder and
father.^

To these we may now turn our attention.

We have seen that even in the first edition of 1543, Vesalius
hinted at his doubts about the Galenic doctrine of the uses of
the heart and its parts, and that in the second edition of 1555
his doubts were more clearly outspoken. That doctrine of
Galen was not merely a wrong conception of a particular part
of physiology, it stood in the way of right conceptions of all
parts of physiology. Let us reflect that to-day our view of any

i] His Forerunners and Followers, 21

and every action and process of the body, has for its fundamental
basis the fact that the life of every tissue unit of the body is
dependent on that unit being bathed directly or indirectly by
blood which comes to it as oxygen-bearing, arterial blood, and
leaves it as venous blood carrying away the products of activity.
Let us remember that such a view is impossible under the
Galenic doctrine which taught that to and from every tissue
there was a flow and ebb of two kinds of blood, serving two
purposes, one kind travelling in the veins, the other in the
arteries. Let us further remember that this Galenic doctrine
of the uses of veins and arteries was bound up with the Galenic
doctrine of the working of the heart. If we do this we shall
at once see that the true teaching of tb^ mechanism of the
bodily heart is as it were the intellectual heart of all phy-
siology, and understand how Harvey in overthrowing the
Galenic doctrine of the action of the heart, overthrew much
more than that, and cleared the way for true conceptions of the
actions of all parts of the body.

The central idea of the Galenic doctrine was the mysterious
transit of blood from the right to the left side of the heart
through the invisible pores of the septum. The transit which
Galen supposed to take place was not a complete transit of the
whole contents of the right ventricle, such as we now know is
effected through the pulmonary circuit, but only a transit of
some of the contents, the rest flowed and ebbed along the
veins, just as the contents of the left ventricle flowed and ebbed
along the arteries. But such a partial transit furnished the
whole intercourse between the right side and the left ; and all
the conceptions of Galen as to what took place in the lungs, in
the arteries, in the veins, and in the heart itself were dependent
on the occurrence of this passage of blood through the appa-
rently solid septum.

We have seen that it was just this part of the Galenic
doctrine which excited Vesalius' strongest doubts and his most
pronounced sarcasm. It was attacked also by others ; some of
these were Vesalius' pupils, direct or indirect, but one was not. _

In Spain, in the land where above all other places the
Church and the Inquisition were stifling inquiry, in Villanueva

r

22 Vesalius: [lect.

in Arragon, there was born in 1511 a man, afterwards known
by the name of Michael Servetus. Fleeing early from the
Inquisition and his native soil, wandering in many lands,
studying many things, learning anatomy under Sylvius and
Giinther at Paris, where he might have sat perhaps on the
same bench with Vesalius, his active mind devoured all the
knowledge of the time. He was in turn jurist, astronomer,
meteorologist, geogi-apher and doctor, but above all other things,
a theologian. He threw himself with zeal into medical studies,
and acquired in them such a reputation that the Archbishop of
Vienna made him his physician ; but his real interest in such
studies lay in his belief that the study of anatomy was one
of the paths which lead to a knowledge of God. To know, said
he, the spirit of God, we must know the spirit of man ; and to
truly know the spirit of man, we must know the structure and
working of the body in which that spirit resides. This led him
to introduce anatomical disquisitions into his theological works.
These were in the main two; one was entitled De Trinitatis
ErrorihuSy published in 1531, through which he stands out in
history as the pioneer of Unitarian doctrine. The other, the
one which most concerns us here, was the Restitutio Christian-
ismi, published in 1553, but ready in manuscript long before.
I need not dwell ^oa. Servetus' story here-j^ Everyone knows
hoWTtt-4553, on Oct. 27, he was burnFaTthe stake in Geneva
at the bidding of Calvin, because he would not recant his
religious faith. With him, or at the same time, there was burnt
the whole edition of 1000 copies of his book, the Restitutio,
with the exception of some few copies which had passed into
the hands of friends.

In the Restitutio occurs this remarkable passage :
"In order, however, that we may understand how the
"blood is the very life, we must first learn the generation
" in substance of the vital spirit itself which is composed and
" nourished out of the inspired air and very subtle blood. The
" vital spirit has its origin in the left ventricle of the heart,
" the lungs especially helping towards its perfection ; it is a
"thin spirit, elaborated by the power of heat, of a yellow
"(light) colour, of a fiery potency so that it is as it were a

i] His Forerunners and Followers. 23

"vapour shining out of the purer blood containing the sub-
" stance of water, of air and of fire. It is generated through
"the commingling which is effected in the lungs of the
"inspired air with the elaborated subtle blood communicated
"from the right ventricle to the left. That communication
" does not, however, as is generally believed, take place through
" the median wall (septum) of the heart, but by a signal artifice
"the subtle blood is driven by a long passage through the
" lungs. It is prepared by the lungs, is rendered yellow (light)
"and from the artery-like vein is poured into the vein-like
"artery. Then in the vein-like artery it is mixed with the
"inspired air, and by expiration is cleansed from its fumes.
" And so at length it is drawn in, a complete mixture, by the
"left ventricle through the Diastole, stuff fit to become the
"vital spirit.

" That the communication and preparation does take place
"in this way through the lungs is shewn by the manifold
"conjunction and communication of the artery-like vein with
" the vein-like artery.

"This view is confirmed by the conspicuous size of the
"artery-like vein which would not have been made so large
" and so stout, and would not discharge from the heart itself such
"a power of very pure blood into the lungs for the mere
"purpose of nourishing these organs. Nor would the heart
" serve the lungs in this manner, especially since at an earlier
" date in the embryo on account of the little membranes of the
"heart, the lungs themselves are up to the hour of birth
"nourished from other sources, as Galen teaches." ^ — "'

These words shew beyond all possible doubt thatl Servetus
rejected wholly and unreservedly the hypothetical passage of
the blood through the septum ; he went far beyond the merely
hinted scepticism of Vesalius. They further shew thatlie had
grasped the true features of the pulmonary circulation, the
passage of the blood from the right side through the lungs to
the left side. He must have attained these results by his own
unaided inquiry and thought ; and had he given to science the
labours which he gave to theology, he obviously might have
deserved the title of one of the great anatomists of the time.

24 Vesalivs. [lect. i

But beyond the above contribution to knowledge, there is
nothing in his works which can be considered as in any way
marking an advance in anatomy or in physiology. Nor is
there any solid reason for thinking that his writings to any
extent influenced the anatomists of the time. Servetus* book,
as we have seen, perished with him, only a few secret copies
surviving, and there is no evidence that these survivors found
their way generally into anatomists' hands ; they were doubtless
treasured by the theologians for whom they were written.

One point however deserves a little notice. The Restitutio
though not published until 1553 was ready in manuscript so
early at least as 1546; and there is evidence that Servetus
sent manuscript copies of it in that year not onlyjto Calvin at
Geneva, but also to one Curio, a learned doctor at Padua. It
has been suggested that Curio might have shewn the work, and
more particularly the passage on which we have dwelt, to
Vesalius, and that this is the reason why Vesalius in his edition
of 1555 was more emphatic in his doubts about the passage
through the septum than he had been in the first edition of
1543, before he had had the opportunity of learning Servetus*
views. But this is a mere guess. Moreover even in 1543
Vesalius, as we have seen, already had his doubts, and in 1555
had he really known and accepted Servetus* statements would,
we may well imagine, have spoken out with a much less uncertain
sound.

I shall have something to say as to the influence Servetus*
words might have had on another man, Realdo Colombo, of whom
we shall have next to speak. But though it cannot be denied that
Servetus was ahead of all his contemporaries in his insight into
the errors of the Galenic doctrine of the heart, it is impossible
to look upon him as one who exerted any marked influence on
anatomical thought. He cannot be regarded as a real link in
the chain which leads from Galen to Harvey and so to the
present day. His utterances are of the same metal, and have
the same ring as those which do form the chain, but they stand
apart from these. His sayings are isolated bits of truths
floating along the stream of human thought by the side of
other truths, the outcome of the labours of other men.

LECTURE II.

HARVEY AND THE CIRCULATION OF THE BLOOD.
THE LACTEALS AND LYMPHATICS.

When in 1542 after the completion of his great work
Vesalius had leave to absent himself from Padua a young
man Matheus Realdus Columbus, a native of Cremona, was
appointed as his deputy, and when in 1544 Vesalius finally
left Padua, the Senate of Venice entrusted for two years
the duty of reading the lectures on Surgery and Anatomy
to the same Columbus. But Columbus did not remain Vesalius'
successor even for the two yeare ; in the next year, 1545, Cosimo
de' Medici appointed him as the first Professor of Anatomy in
the newly renovated University of Pisa ; and Vesalius' chair
was not adequately filled until 1551, when Gabrielus Fajloppius
was placed in it.

Falloppius, bom in Modena in 1523, a favourite and a
devoted pupil of Vesalius, an accomplished and travelled
scholar, a careful and exact observer and describer, a faithful,
modest, quiet man has left his name in anatomy, in the terms
Falloppian canal and Falloppian tubes. We owe to him
many valuable observations on the skeleton, especially on
the skull, on the tympanum, on the muscles, and on the
generative organs. But he made no large contribution to
knowledge such as distinctly influenced the progress of physio-
logy ; and he left no mark on the doctrines of the circulation.
I have already spoken of his Anatomical Observations as
stirring up Vesalius in his later years to revived anatomical

26 Harvey and the [lect.

longings ; in these Falloppius says that if he had been able to
advance any new truth, that was largely due to Vesalius
" who so shewed me the true path of inquiry that I was able
"to walk along it still farther than had been done before."

A very different man was Matheus Realdus Columbus.
Bom at Cremona in 1516, and therefore only a year or so
younger than Vesalius, he came at the close of his * teens ' to
Venice and Padua to study medicine. He says that he learnt
all he knew from one Lonigo; but there can be no doubt that he
also studied under and learnt much from Vesalius, who indeed
says that he was very intimate with him (mihi admodum
familiaris). Apparently at first Vesalius thought very highly
of his Cremonian friend; but it was not long before the
two became estranged; and with reason. Columbus was evi-
dently a sharp, clever, man ; but not only did he lack a good
general education, such as Vesalius, Falloppius and others en-
joyed in a high degree for they had studied Greek and
philosophy as well as Latin, whereas Columbus seems to have
been imperfectly acquainted even with Latin ; his professional
knowledge also was superficial. Vesalius spoke of him in later
years as an uncultivated smatterer. So far from appreciating
Vesalius' greatness, Columbus seemed to have thought that he
was as good as he and that he ought to receive the like high
reputation. When and wherever a Goliath appears we find
some young would-be David starting up to win fame by
throwing the stone at him ; and Columbus, while acting as
Vesalius' deputy, thought that Vesalius' absence was his
opportunity, and in the anatomical theatre he insisted often
and loudly on Vesalius' errors; he did his best to make
Vesalius ridiculous, and to prove that the great anatomist of
the time was not he but Matheus Realdus Columbus. Vesalius
however on his return turned the tables on him, and thoroughly
exposed his pretentions.

Again and again, in the story of the time we find indi-
cations of something unsatisfactory about Columbus. The
Venetian Archives contain two records for the year 1541,
one in August nominating for the chair of Surgery in Padua
in the first place Andreas Vesalius, and in the second place

n] Circulation of the Blood. 27

Matheus Realdus Colombus, another in October confirming
the above but omitting Columbus " for we wish Vesalius alone
" to read the Lecture on Surgery." This suggests that the first
nomination of Columbus had been gained by means of which
the Senate did not approve. Later on when in 1542 Vesalius
left Padua for a while, there is evidence that Columbus, though
appointed deputy, did not wholly replace the absent professor ;
he did the dissections, and he was probably a very skilful
workman, but it would appear that one Montanus read the
lecture. Lastly, upon Vesalius' final departure in 1544, though
the records shew that Columbus was, as we have said, formally
appointed his successor for two years certain, he only retained
the chair for a year ; in 1545 he withdrew to Pisa.

The great Florentine patrons of science and art were then
striving to make a famous University at Pisa. As we shall
see they so far succeeded that in later years Pisa outshone
Padua, Bologna and Rome ; but at the time of which we are
speaking, a chair at Pisa was something like a chair now-a-days
in a small provincial College, a post sought after as an oppor-
tunity for winning one's spurs, a stepping-stone to better and
higher things. It was such to Falloppius, who professed
anatomy there from 1548 until his call to Padua in 1551.
Columbus* going to Pisa was therefore not a step in the way
of preferment ; some other reason must have been the cause of
his leaving Padua. He taught anatomy at Pisa until 1548,
when he received a call to the chair of anatomy in the University
at Rome, which he held until his early death in 1559.

He left behind him one work only, his De Re Anatomica
IMyri XV. published by his children in 1559 after his death.
That book though it achieved fame, and indeed Harvey spoke
of its author with respect as of a great authority, is a mirror of
Columbus' character and attainments. It is, though much
shorter, an almost barefaced imitation of Vesalius' Fahrica,
The frontispiece even is a bad imitation of Vesalius' frontis-
piece, and the work ends as does Vesalius' with a chapter
on vivisection, the one being little more than a varied
repetition of the other. Throughout the work are tokens
of the vain man striving to exalt his own horn. He tells us

28 Harvey mid the [lect.

again and again how much he impressed his listeners. " When
" I shewed this to His Eminence, he expressed himself as hugely
" gi'atified." " When I gave the demonstration of this important
"new truth, I had the honour to count among my audience
** His Royal Highness this. His Excellency that, and the Most
" Reverend the other/' He left no stone unturned with which
he might hope to increase men's acknowledgment of his talents,
and there are many reasons for thinking that his position
at Rome was in large measure dependent on his fulsome
adulation of Pope Pius IV., to whom his posthumous work
was dedicated. They who know the character of Pius IV. can
judge of the character of the man who loaded him with praises.

Nevertheless, vain as Columbus certainly was, ignorant also
in many respects as he seems to have been, there is no doubt
that in the work of which we have spoken he did correctly
describe the pulmonary circulation. This is what he says
in his chapter on the heart and arteries: —

*' Two cavities that is two ventricles, are present in the heart,
" not three as Aristotle thought. Of these one is on the right
" side, the other on the left. The right is much larger than
"the left. The right contains the natural blood, but the left
" the vital blood. It is very interesting to observe that the
" substance of the heart surrounding the right ventricle is very
" thin but on the left side is very thick ; and this is so arranged
"on the one hand in order to keep up the balance and
" on the other to prevent the vital blood which is exceedingly
"thin from transuding out of the heart. Between these
"ventricles there is placed the septum through which almost
"all authors think there is a way open from the right to
"the left ventricle; and according to them the blood is in
"the transit rendered thin by the generation of the vital
" spirits in order that the passage may take place more easily.
" But these make a great mistake ; for the blood is carried by
"the artery-like vein to the lung and being there made thin
"is brought back thence together with air by the vein-like
"artery to the left ventricle of the heart. This fact no one
** has hitherto observed or recorded in writing ; yet it may be
" most readily observed by anyone."

n] Circulation of the Blood. 29

And again, speaking of the vein-like artery he says :
"Anatomists, not very wise, begging their pardon, in so
" doing think that the use of this is to carry the changed air to
" the lungs which, like a fan, ventilate the heart, cooling this
"organ and not as Aristotle thought, the brain. The same
"writers think that the lungs receive the I know not what
"smoky fumes (fumos capinosos) (for so in their ignorance
"of the tongues they call them) discharged from the left
" ventricle. About this, all one can say is that it pleases them,
" for they certainly seem to think that the same state of things
" exists in the heart as in a chimney, as if there were green
" logs in the heart which give out smoke when burnt. So far
" concerning the use of these parts according to the opinion of
** other anatomists. I for my part hold a quite diflferent view,
"namely that this vein-like artery was made to carry blood
" mixed with air from the lungs to the left ventricle of the
" heart. And this is not only most probable, but is actually
" the case ; for if you examine not only dead bodies but also
** living animals, you will find this artery in all instances filled
" with blood, which by no manner of means would be the case
"if it were constructed to carry air forsooth and vapours.
" Wherefore I cannot wonder enough at those anatomists who
" have not observed a matter so clear and of such importance,
" eminent though they wish to be considered and indeed are
"considered by many of their fellows. But for these it is
" enough that Galen said so. What ? To think that some
" folk in our time swear to the dogmas of Galen about anatomy
" so that they dare to assert that Galen ought to be taken as
" gospel, and that there is nothing in his writings which is not
" true ! It is wonderful how men are carried away by this
" doctrine; and the princes of the anatomy oflfer it to the rabble.
" Yet no one sees how much this is to be blamed. Who indeed
" is there who never offends ? But of this enough and more
" than enough."

He without restriction claims the discovery as his own.
Let me note in passing that he makes no attempt to draw
from the important new fact, the conclusions which chiefly
give it its importance. Though he repudiates the Galenic

30 Harvey mid the [lect.

doctrine of the passage through the solid septum, the changed
view on this point makes no essential change in his general
views on the circulation. These still remain Galenic; the
veins still carry blood to all parts of the body. "This is the
" use of the veins, to carry blood to all parts of the body in
" order to nourish them ; for all the members of the body are
" nourished by blood alone, wherefore nature made the veins
" hollow for the sake of their function that like streams they
" might pervade the body." He did not grasp the true mean-
ing of the discovery on which he prides himself, and others
after him as we shall see also failed to see it. But did he
really himself make the discovery ?

His book as we have seen was not published until 1559.
In no other writing had he published the discovery ; we have
no record of when he began to teach this new doctrine of the
pulmonary circulation. He may have taught it orally to his
students, or its appearance in the posthumous work may have
been the first occasion of its being made known. We cannot
tell ; but we may be well sure that he had not arrived at the
new truth before he came to Rome while he was still at Padua
or Pisa, seeking to win fame.

Now his teaching of the pulmonary circulation is almost
identical with that of Servetus, and resembles it in the absence
of the far-reaching conclusions which may be drawn from the
fact.

As we have seen Servetus in 1546 sent to Curio in Padua
a manuscript copy of his Restitutio ; this Columbus may have
seen. Again when the edition of the published Restitutio was
burnt in 1553, some few copies escaped ; one of these may have
found its way to Rome before Columbus had sent his work
to the press.

Columbus might have taken the idea from Servetus. But
what right have we to accuse Columbus of what is in reality
a theft? Vesalius too might have seen if not Curio's manuscript
copy, at least one of the escaped prints of 1553, before he
published the second edition of his Fabrica in 1555. But
Vesalius does not describe the pulmonary circulation; in his
edition of 1555, he merely accentuates the doubts about the

n] Circulation of the Blood. 31

Galenic doctrine which he felt in 1543. Columbus almost exactly
repeats Servetus' words.

Moreover we have clear evidence that in the same book
De Re Anatomica he did claim as his own discovery, something
which we know he learnt from others. In that work he states
that he was the first to describe the third ossicle of the ear,
the stapes. But we know from Falloppius that the stapes
was first observed and described by John Philipp Ingrassias of
Palermo, or rather of Rachelburg, a Sicilian of eminence, who
ultimately succeeded Vesalius as physician to Philip II.
Ingrassias' discovery was made known in 1548 to Falloppius, who
inquiring of his friends at Rome about it was assured by them
that neither Columbus nor any one else had ever mentioned it.

We have here evidence not only of a theft but of a bold
theft, of an unabashed attempt to assert ownership of the thing
thieved. He who sins once may be looked for to sin again ; and
we may with reason suspect that Columbus' asserted discover}'
of the pulmonary circulation was not his own but Servetus*.

Still the fact remains that this marked departure from the
Gralenic doctrine was clearly enunciated by him, and that not,
as had been done by Servetus, in an out of the way manner as
a link in a theological argument, but conspicuously as part of a
description of the heart in an important anatomical treatise.

Of a very different stamp to Columbus was Andreas
Caesalpinus. Bom at Arezzo in 1519, he was for many years
Professor of Medicine at Pisa, namely from 1567 to 1592, when
he passed to Rome where he became Professor at the Sapienza
University, and physician to Pope Clement VIII., and where
at a ripe old age he died in 1603.

If Columbus lacked general culture Caesalpinus was drowned
in it. Learned in all the learning of the ancients and an
enthusiastic Aristotelian, he also early laid hold of all the new
learning of the time. Naturalist as well as physician, he
taught at Pisa Botany as well as Medicine, being from 1555
to 1575 Professor of Botany with charge of the Botanic garden
founded there in 1543, the first of its kind, one remaining
until the present day.

He made no marked contribution, of a clear and definite

32 Harvey mid the [lect.

nature to our knowledge of the structure or working of the
animal body; he was indeed not an observer, but a theorist
and perhaps even more a disputer. His real passion seems to
have been for theology, his studies in which led him for a while
into a conflict with the church, though he ultimately recanted his
heresy. His favourite doctrine was that the world was peopled
with and indeed ruled by invisible demons, the apparently
voluntary acts of every man being in reality the handiwork of
the man's own familiar spirit. In all that related to medicine
he early took up an attitude of opposition to Galen, carrying
it almost to the extent of maintaining that whatever Galen
affirmed was wrong, and that whatever Galen opposed was
right. It would, seem that it was this spirit of the controver-
sialist rather than any careful observation of and deduction from
phenomena which led him in his rambling discursive and
obscurely written philosophical and medical treatises, his
Quaestiones peripateticae (1571), and his Questiones Medicae
(1593), to enunciate views, which however he arrived at them
certainly foreshadowed or even anticipated those which were
later on to be established on a sound basis.

In his Peripatetic Questions he seemed to have hold of
several points relating to the true action of the heart. He says
for instance Lib. v. Quaest. 4 :

" For the membranes are so placed at the orifices that they
" are opened when the heart is dilated and are closed when the
" heart is contracted. It follows therefore either that the lung
" and heart must be dilated at the same time and constricted at
" the same time ; or the entrance of the spirits must take place
" while we breathe out. For if the heart happens to be dilated
" while the lung is constricted, and to be constricted while it is
" dilated, the air will enter the heart when we breathe out and
" issue from the heart when we breathe in ; which is impossible
" for the movements are in a contrary direction. To say, however,
" that the heart and lung are always dilated at the same time
" and contracted at the same time is opposed to facts, for we can
" regulate our breathing by our will, but the beat of the heart
" is wholly beyond our power ; and even when we are breathing
" involuntarily, breathing is in most cases slower than the pulse.

n] Circulation of the Blood, 33

"The pulse of the arteries presents another difficulty.
"Of the vessels ending in the heart, some send into it the
"material which they carry, for instance the vena cava into
" the right ventricle, and the vein-like artery into the left ; some
" on the other hand carry material away from the heart, as for
" instance the aorta artery in the left ventricle and the artery-
" like vein nourishing the lung in the right. To each orifice are
" attached little membranes whose function is to secure that the
" orifices letting in do not lead out and that those leading out do
" not let in. It follows that when the heart contracts the arteries
" are dilated, and when it is dilated they are constricted; the two
" are not, it appears, constricted and dilated together. For when
" the heart is dilated, it wishes that the orifices of the vessels
"which lead out should be shut so that material should not flow
"from the heart into the arteries, but that it should flow in
" this way when the heart contracts, the membranes gaping (and
" aflFording a passage). If therefore the arteries were dilated and
" constricted at the same time as the heart, it would follow that
" they would be dilated at the time when the material filling
"them from the heart was denied them, and constricted at a
" time when material was flowing into them from it. But it
"is manifest that this is impossible. To say therefore that
" the heart and arteries beat at diflFerent times is to deny one's
" senses and to doubt reason."

He thus appears to have grasped the important truth,
hidden, it would seem, from all before him, that the heart, at
its systole, discharges its contents into the aorta (and pul-
monary artery), and at its diastole receives blood from the
vena cava (and pulmonary vein).

Again, in his Medical Questions, he seems to have grasped
the facts of the flow from the arteries to the veins, and of the
flow along the veins to the heart. He says. Lib. ii. Quaest. 17,

" But the following matter seems worthy of consideration,
" the reason, namely, why veins when ligatured swell on the fer
" side and not on the near side of the ligature. This is a fact
"well known by experience to those who let blood; for they
" place the ligature on the near side of the place of incision,
"not on the far side, because the veins swell on the far side,
p. L. 3

34 Harvey and the [lect.

" not on the near side of the ligature. But exactly the contrary
" ought to happen if the movement of the blood and the spirits
"took place in the direction from the viscera to all parts of
"the body. When a channel is interrupted, the flow beyond
" the interruption ceases ; the swelling of the veins therefore
"ought to be on the near side of the ligature.

" Here is the solution of the doubt arising from what Aris-
" totle writes concerning sleep when he says : ' It is necessary
" ' that what is evaporated should be driven to some place and
" * then be turned back and changed like Euripus. For the heat
" * of every living thing ascends by nature to a higher place,
" * but when it has rfeached the higher place, it in many cases
" ' turns back again and is carried downwards.* This is what
" Aristotle says. Now to explain this passage we must recognize
" the following. The passages of the heart are so arranged by
" nature that from the vena cava a flow takes place into the
" right ventricle, whence the way is open into the lung. From
"the lung moreover there is another entrance into the left
" ventricle of the heart, from which then a way is open into the
" aorta artery, certain membranes being so placed at the mouths
"of the vessels that they prevent return. Thus there is a sort
" of perpetual movement from the vena cava through the heart
"and lungs into the aorta artery as I have explained in my
"Peripatetic Questions.

" Now when we are awake the movement of the native heat
" takes place in a direction outwards, namely, to the sensory
" regions of the brain. When we are asleep however it takes
" place in the contrary direction towards the heart. We must
" therefore conclude that when we are awake a large supply of
" blood and of spirits is conveyed to the arteries and thence to
" the nerves. When we are asleep however the same heat is
" carried back to the heart not by the arteries but by the veins.
" For the natural entrance into the heart is ftirnished by the
" vena cava, not by the arteries. A proof of this may be seen in
" the pulses, which when we jire wide awake are full, vehement,
" quick, with a certain rapidly repeated vibration, but when we
"are asleep are small, languid, slow and infrequent. For in
" sleep the supply of native heat to the arteries is diminished,

ii] Circulation of the Blood. 35

** but it bursts into them with vehemence when we wake. The
" veins however behave in an opposite manner ; for when we are
" asleep they are more swollen, when we are awake they are
" shrunken, as anyone may see who watches the veins in the
" hands. For when we are asleep the native heat passes from
" the arteries by that communication of orifices which we call
" anastomosis into the veins and so to the heart. As however
" this flowing out of blood to the higher regions, and its return
"to lower regions like a Euripus is manifest in sleep and
" wakefulness, so also a movement of the same kind is obvious
" in every part of the body to which a ligature is applied, or
" where the veins are blocked in any other way. For when its
"free channel is obstructed, a stream swells at the point to-
" wards which it is accustomed to flow. The blood then rushes
"forcibly back to its source, lest, being cut off*, it should be
" extinguished."

We must therefore admit that Caisalpinus had not only
clearly grasped the pulmonary circulation, but had also laid
hold of the systemic circulation ; he recognized that the flow of
blood to the tissues took place by the arteries and by the
arteries alone, and that the return of the blood from the
tissues took place by the veins and not by the arteries.

In respect to these important points, he had obviously
freed himself from the Galenic doctrine. But the question
may fairly be asked. How far were these views the outcome
of patient research, of real study of the phenomena themselves?
How far were they flung out in the spirit of controversy
as eflFective assaults upon accepted doctrines?

We may feel inclined to take the latter view when we
notice how little acceptance C«salpinus*s new doctrines met
with among his contemporaries; how little heed indeed was
paid to them until they were disinterred, so to speak, by
antiquarian research, and in particular what little influence
they seemed to have exerted upon Csesalpinus*s great con-
temporary who made the next great step in the advance of the
true theory of the circulation, I mean Hieronymus Fabricius,
often spoken of, from the place of his birth, as ab Aquapendente.

Bom, in 1537, of humble parents, in the little Tuscan town

3—2

36 Harvey and the [lect.

or rather village bearing that name, Fabricius studied under
Falloppius at Padua, and, on the death of his master, in 1565,
succeeded him in the chair of Anatomy, holding it for 40 years,
until 1619, when he died at the ripe old age of 82.

A distinguished surgeon and a learned anatomist, well
acquainted with the anatomy not only of man but of other
vertebrates, he was the author of many treatises, most of which
had distinct physiological bearings and which contained many
contributions to the advancement of knowledge. He wa5 the
first after Aristotle to describe the formation of the chick in
the egg ; he wrote well on locomotion, on the eye, on the ear,
on the skin, on the larynx and on speech; but the one work
which concerns the subject which we have in hand is that on
the valves of the , veins, the book Be venarum ostiolis, ' the
little doors of the veins,' which saw the light in 1574.

Johannus Baptista Cannanus, Professor at Ferrara, is said to
have observed the valves long before, namely in 1547, and
indeed to have told Vesalius of his observation; and even
before that, these structures it is said were noticed by Sylvius.
But they were not really laid hold of until Fabricius published
his book. In that work he most carefully and accurately
described their structure, position and distribution, illustrating
his observations by fairly good figures. He moreover clearly
recognized that the valves offered opposition to the flow of
blood firom the heart towards the periphery, and even gives
the now well-known demonstration of their action on the living
arm.

He says De Venarum Ostiolis :

" Little doora of the veins is the name I give to certain very
"thin little membranes occurring on the inside of the veins,
" and distributed at intervals over the limbs, placed sometimes
" one by itself, and sometimes two together. They have their
" mouths directed towards the root of the veins (i.e. the heart),
" and in the other direction are closed. Viewed from the outside
** they present an appearance not unlike the swellings which are
" seen in the branches and stem of a plant. In my opinion they
"are formed by nature in order that they may to a certain
" extent delay the blood and so prevent the whole of it flowing

n] Circulation of the Blood. 37

"at once like a flood either to the feet, or to the hands and
"fingers, and becoming collected there. For this would give
"rise to two evils; on the one hand the upper parts of the
"limbs would suffer from want of nourishment, and on the
"other the hands and feet would be troubled with a con-
"tinual swelling. In order therefore that the blood should
"be everywhere distributed in a certain just measure and
"admirable proportion for maintaining the nourishment of
" the several parts, these valves of the veins were formed.

"In the veins laid bare and examined untouched, these
" valves are visible to a certain extent. Nay more, that even in
" the living arm or thigh these valves may give evidence of their
" existence appears clearly from the fact that, when in letting
"blood the assistants bind the limbs, at intervals along the
" course of the veins, little knots as it were are seen from the
" outside ; these are swellings caused by the valves.

"That indeed the flow of the blood is slowed by means
" of these valves is not only made clear by their construction
" but also is shewn by the following experiment which anyone
" can make, either by laying bare the veins in a dead body, or
" by ligaturing a limb in a living body, as they do when they
" let blood. For if you attempt to press, or by rubbing to drive
"the blood downwards (towards the hand for instance) you
"will cleai'ly see that its flow is prevented and delayed by
"the valves.*'

But he wholly failed to recognize their true function. Still
labouring under the influence of the old doctrines and believing
that the use of the veins was that of carrying crude blood,
blood not vivified by the vital spirits, from the heart to the
tissues, he thought that he had fully explained the value of the
veins, by pointing out that they opposed the flow from the
heart to the tissues, not of all blood but only of an excess of
blood; their purpose was to prevent the blood as it flowed
along the veins from the heart being heaped up too much in
one place. But he also thought that they were the means of
ftimishing temporary local reservoirs of blood ; and he likens

38 Harvey mid the [lect.

them to the devices by which in mills and elsewhere water is
dammed up. He left for another, for a pupil of his, the oppor-
tunity of putting to its right use the discovery which he had
made.

Though he wrote on many points of physiology, Fabricius
did not grapple with the problems of the heart. We learn his
views on these incidentally from his treatise, De respiratiane et
ejus ingtrumentis, written in 1599, but not published until
1603. The greater part of this work deals and deals well with
the muscles and with the general mechanism of respiration,
but in it he also speaks of the relation of respiration to the
work of the heart.

In view of the importance of rightly appreciating the
value of the great work which was to appear a quarter of a
century later, it may be worth while to ask what were the views
concerning the circulation which at the close of the sixteenth
century were being expounded by this great teacher, whose
lectures were attended by such crowded classes, that a new
great theatre had to be built for him, who was drawing hearers
to him, not only from all Italy, but from all parts of Europe,
even from distant Britain, and who by his fame, maintained
and even increased the reputation of the great school of Padua.

Strange as it may seem, the teaching of Fabricius in 1599
was little more than a repetition of the teaching of Galen ; and
it is worthy of notice that in this treatise, while he repeatedly
refers to Galen, he hardly at all refers to Vesalius, or to any
other modern anatomist.

This is what he says :

" Admitting then that the lungs are composed of their own
" proper tissue, of the artery-like vein, of the vein-like artery
" and of the rough artery (trachea), and that they possess the
"artery-like vein for the purposes of their own nourishment,
" that they possess their own proper tissue to act like tow for
" the purpose of supporting and guarding the terminations of
" the vessels, and that they possess the rough artery, in order
"that there may be a fit receptacle for receiving the air,
" admitting this, it would nevertheless seem altogether reasonable
" to think that the whole construction of the lungs was carried

n] Circulation of the Blood. 39

" out chiefly for the sake of the remaining vessel, namely, the
"vein-like artery which seizes upon the air in the lungs and
" carries it to the heart, the same forsooth being drawn through
•* them by the heart. It is thus reasonable to suppose that the
"lungs exist for the sake of the vein-like artery, the use of
" which is that the air may conveniently reach the heart ; for
"otherwise the air would be drawn into the cavity of the
"thorax and would never reach the heart did not the heart
"extend its vein-like artery from its left sinus right up into
"the lungs."

And in his Epilogus he thus sums up :

" In breathing. Nature puts before herself mainly a double
" goal, the generation of the animal spirits, and the regulation and
" conservation of the heat of the heart. The heat is maintained
" and regulated by the supply of material, by refrigeration, and
" by getting rid of superfluous residues. All these things are
"brought about by means of the air taken into the body,
"whence the necessity of breathing. This breathing is the
"bringing in of air by which spirit is carried inwards and
"outwards through the mouth,. and is divided into inspiration
'*and expiration. In inspiration air enters the lungs and the
" heart for the sake of the supply of material and of refrigera-
" tion ; in expiration, on the other hand, the air issues for the
" sake of getting rid of superfluous residues. The air enters by
"being drawn in, it issues by being driven out; it is drawn
**in, not by any occult virtues or influences, but only by the
" principle that a vacuum must be filled up."

In spite of many clear views as to the mechanics of respira-
tion, he holds that the air is carried to the heart by the
vein-like artery, and much of his work is taken up in a long
discussion as to the exact way in which the air thus entering
affects on the one hand the generation of the vital spirits, and
on the other hand the innate heat of the heart.

" If all this belongs to the innate heat of the heart which
" bums as with a flame, it must in any case be maintained that
" the whole business of maintaining and regulating that heat
" consists in the first place of providing material (for the flame),
" then of ventilation, then of moderate refrigeration, and lastly

40 Harvey and the [lbct.

" of the discharge of fumes ; all these are supplied by respira-
" tion."

In his treatise on the formation of the foetus he says :

" The lungs while (in the adult) they are doing work for the
" good of the whole body, make use in the following manner of
"the three kinds of vessels which penetrate their substance,
" namely, the rough artery, the artery-like vein, and the vein-like
** artery. By means of the rough artery they are the first to seize
"upon and receive the air drawn in by respiration, which
" subsequently by the beat of the heart is carried through the
" vein-like artery into the left cavity of the heart, to be elaborated
" and converted into vital spirits and at the same time to afford
"refrigeration for the heart. By means of the third vessel,
"which is spoken of as the artery-like vein, the lungs are
" nourished with the purest and thinnest blood. Hence, during
"this time, the lung is nourished by a vessel possessing the
" structure of an artery, but indeed receives spirits by a vessel
"which has the substance of a vein. But while the foetus is
" being carried in the uterus, since the lung does not carry out
"the function of respiration, but attends only to its own
" business, the change of function is accompanied by a change
" of structure. For it lays hold of blood for its own nutrition
" by means of the venous vessel, but draws in vital spirits by an
" arterial vessel."

All this is sheer Galenism, with here and there a modem
touch. It may be worth while to call to mind that the man
who in 1599 wrote this was the pupil, a favourite pupil, of
Falloppius, who was in turn the favourite pupil of Yesalius,
and that the atmosphere around the chair of Anatomy at Padua
must have been thick with the memories and traditions of the
teachings of these great men.

He had probably heard Falloppius tell many a saying of
Vesalius, many an expression of the great man's not embodied
in the written work. He probably bade his hearers take
Vesalius* great work as their text-book, that great work in
which Vesalius, by his insistance of the value of original inquiry
as against the mere following of authority, and no less by the
free expression of his doubts concerning current doctrines and

n] Circfulation of the Blood. 41

of the need of putting these to the test of examination, had
boldly cleared the way for future research. Even if he had
not read Servetus, he must have been familiar with Columbus's
book ; and both of these (we may lay on one side for the moment
the possible connection between the two) had declared against
the mysterious passage through the solid septum and in favour
of the flow through the lungs, from the right side to the left
side of the heart. He could not have been ignorant of the
writings of Caesalpinus, who had so boldly expounded his views
as to the action of the heart, and the flow along the veins from
the tissues to the heart. He himself had contributed that
knowledge of the valves of the veins, which rightly used
overturned the whole Galenic doctrine. Yet it was then, as it is
now to-day, as it has been in every period between then and
now, as it was in all times before, and as it will be so far as we
can see in all times to come. So strong was the hold upon
his mind of conceptions coming down from the past, that
Fabricius's eyes were blinded to facts staring him in the face, and
his ears were deaf to voices crying out new views. At almost
the very parting of the ways he continued calmly to preach
that the old way was the better one, the way in which men
should walk.

It was left for a pupil of his to seize that which he had just
failed to lay hold of, to weld together, as he was passing away,
into one sustained and convincing argument, the several links
which he and the rest had furnished, and nine years after his
death to make known to the world that true view of the
circulation which was the real beginning of modem physiology.

I need not take up time by entering largely into the details
of the oft-told story of William Harvey's life.

Bom at Folkestone, on the south coast of England, in April,
1678, just four years after Fabricius had published his treatise
on the valves of the veins, admitted to Gonville and Caius
College, Cambridge, in 1593, taking his degree in Arts in
1597, he left England the following year to study medicine
under the great master at Padua. There he spent the greater
part of four years, years very nearly overlapping the period

42 Harvey and the [lect.

between the writing and the publication of Fabricius's treatise
on Respiration, of which I have just spoken as being, in great
measure, an exposition of the Galenic doctrine of the circulation.
At the end of the period, in 1602, he received at Padua the
degree of Doctor of Medicine, and on his return to England
in the same year was incorporated into the Doctorate at
Cambridge.

Setting up his abode in London, joining the Royal College of
Physicians in 1604, and becoming Physician to St Bartholomew's
Hospital in 1609, he ventured in 1615 to develope, in his
Lectures on Anatomy at the College of Physicians, the view
which he was forming concerning the movements of the heart
and of the blood. But his book, his Exercitatio, on that
subject did not see the light until 1628.

' The little choleric man ' as Aubrey calls him, attained fame
among his fellows, and favour at Court. As Physician to King
Charles I. he accompanied that Monarch on his unhappy
wanderings, and every one knows the tale or legend of how at
the battle of Edgehill, taking care of the Princes he sat, on the
outskirts of the fight under a hedge, reading a book. In 1646,
after the events at Oxford, he retired into private life, pub-
lishing in 1651 his treatise, De generatione animalium, in
which he followed up some of the researches of his Paduan
master, and on June 3, 1667, he ended a life remarkable for
its effects rather than for its events.

It is a fashion to speak of Harvey as * the immortal Dis-
coverer of the Circulation ; ' but the real character of his work
is put in a truer light when we say that he was the first to
demonstrate the circulation of the blood. His wonderful book,
or rather tract, for it is little more, is one sustained and
condensed argument, but an argument founded not on general
principles and analogies but on the results of repeated ' frequent
appeals to vivisection ' and ocular inspection. He makes good
one position, and having done that advances on to another, and
so marches victoriously from position to position until the whole
truth is put clearly before the reader, and all that remains is to
drive the truth home by fui-ther striking illustrations.

His first position is the true nature and purpose of the

ii] Circulation of the Blood. 43

movements of the heart itself, that is of the ventricles. When,
in the beginning of the inquiry, he 'first gave his mind to
vivisections * he found the task of understanding the * motions
and uses of the heart so truly arduous, so full of difficulties '
that he began to think with Fracastorius (a Veronese doctor
of the middle of the sixteenth century (1530) and more a poet
than a man of science), " that the motion of the heart was only
to be comprehended by God." But the patient and prolonged
study of many hearts of many animals shewed him that " the
motion of the heart consists in a certain universal tension, both
of contraction in the line of its fibres, and constriction in every
sense, that when the heart contracts it is emptied, that the
motion which is in general regarded as the diastole of the heart
is in truth its systole," that the active phase of the heart is not
that which sucks blood in, but that which drives blood out.
Ciesalpinus alone, as we have seen, of all Harvey's forerunners
had in some way or other dimly seen this truth. Harvey saw
it clearly and saw it in all its consequences. It is, he says, the
pressure of the constriction, of the systole, which squeezes the
blood into and along the arteries, it is this transmitted pressure
which causes the pulses; the artery swells at this point or
that along its course, not in order that it may suck blood into
it, but because blood is driven into it, and that by the pressure
of the constricting systole of the heart.

With this new light shining in upon him, he was led to
a clear conception of the work of the auricles and the ventricles,
with their respective valves* He saw how the vena cava,
on the one side, and the vein-like artery, the pulmonary veins
on the other side, empty themselves into and fill the ventricles
during the diastole, and how the ventricles in turn empty
themselves during the systole, into the artery-like vein, the
pulmonary artery on the one side and the great artery or
aorta on the other. And this at once led him to a truer
conception of the pulmonary circulation than was ever
grasped by Servetus or Columbus. On the old view, only some
of the blood of the right ventricle passed through the septum
into the left ventricle ; the rest went back again to the tissues ;
and it was this *some' only which Servetus and Columbus

44 Harvey mid the [lect.

believed to pass through not the septum but the lungs. Harvey
saw that all the reasons for thinking that any of the contents
of the ventricle so passed, were equally valid for thinking that
all passed, and that the latter view alone was consonant with
the facts.

This new view, new in reality, though having so much
resemblance to old ones that Harvey speaks of it as one " to
"which some, moved either by the authority of Galen or
"Columbus or the reasonings of others will give their ad-
" hesion," led him at once to another conception which however
** was so new, was of so novel and unheard of a character that
" in putting it forward he not only feared injury to himself from
" the envy of a few, but trembled lest he might have mankind
"at large for his enemies." This new view consisted simply in
applying to the greater circulation the same conclusions as
those at which he had arrived in regard to the lesser circulation.

It is important to note that to this new view he was guided
by distinctly quantitative considerations. He argued in this way.
At each beat of the heart a quantity of blood is transferred
from the vena cava to the aorta. Even if we take a low
estimate (he had made observations with a view to determining
the exact amount but he leaves this aside for the present as
unessential), say half an ounce, or three drachms, or only one
drachm, and multiply this by the number of beats, say in half-
an-hour, we shall find that the heart sends through the arteries
to the tissues during that period as much blood as is contained
in the whole body. It is obvious, therefore, that the blood
which the heart sends along the arteries to the tissues cannot
be supplied merely by that blood which exists in the veins as
the result of the ingesta of food and drink ; only a small part
can be so accounted for ; the greater part of that blood must be
blood which has returned from the tissues to the veins; the
blood in the tissues passes from the arteries to the veins, in
some such way as in the lungs it passes from the veins (through
the heart) to the arteries ; the blood moves in a circle from the
left side of the heart, through the arteries, the tissues and the
veins to the right side of the heart, and from thence through
the lungs to the left side of the heart.

n] Circulation of the Blood. 45

This is what he says :

" I frequently and seriously bethought me, and long revolved
" in my mind, what might be the quantity of blood which was
" transmitted, in how shoi*t a time its passage might be eflTected,
*' and the like ; and not finding it possible that this could be
*' supplied by the juices of the ingested aliment without the
" veins on the one hand becoming drained, and the arteries on
"the other hand becoming ruptured through the excessive
" charge of blood, unless the blood should somehow find its way
" from the arteries into the veins, and so return to the right
" side of the heart ; I began to think whether there might not
" be a motion, as it were, in a circle. Now this I afterwards
" found to be true ; and I finally saw that the blood, forced by
"the action of the left ventricle into the arteries, was dis-
"tributed to the body at large, and its several parts, in the
" same manner as it is sent through the lungs, impelled by the
"right ventricle into the pulmonary artery, and that it then
"passed through the veins and along the vena cava, and so
" round to the left ventricle in the manner already indicated,
"which motion we may be allowed to call circular."

As the sun of this truly new idea rose in Harvey's mind, this
new idea that the blood is thus for ever moving in a circle, the
mists and clouds of many of the conceptions of old faded away
and the features of the physiological landscape hitherto hidden
came into view sharp and clear. This idea once grasped, fiwt
after fact came forward to support and enforce it. It was now
clear why the heart was emptied when the vena cava was tied,
why it was filled to distension when the aorta was tied. It was
now clear why a middling ligature which pressed only or chiefly
on the veins made a limb swell turgid with blood, whereas a tight
ligature which blocked the arteries made it bloodless and pale.
It was now clear why the whole or nearly the whole of the
blood of the body could be drained away by an opening made
in a single vein. And now for the first time was clear the
purpose of those valves in the veins, whose structure and
position had been demonstrated doubtless to Harvey, by the
very hands of their discoverer, his old master Fabricius, but
"who did not rightly understand their use, and concerning

46 Harvey a^id the [lect.

which succeeding anatomists have not added anything to our
knowledge."

Fabricius, as we have seen, had used the now well-worn
experiment of pressing on the cutaneous veins of the bared
arm to demonstrate the existence of the valves; but he
had used it to demonstrate their existence only. Blinded
by the conceptions of his time he could not see that the
same experiment gave the lie to his explanation of the pur-
pose of the valves, and demonstrated not only their existence,
but also their real use. Harvey, with the light of his new idea,
at once grasped the true meaning of the knotty bulgings.

These however were not the only phenomena which now for
the first time received a reasonable explanation. Harvey was able
to point to many other things, to various details of the structure
and working of the heart, to various phenomena of the body
at large both in health and in disease as intelligible on his
new view, but incomprehensible on any other.

If we trust, as indeed we must do, Harvey's own account of
the growth of this new idea in his own mind, we find that he
was not led to it in a straight and direct way by Fabricius'
discovery of the valves. It was not that the true action of
these led to the true view of the motion of the blood, but that
the true view of the motion of the blood led to the true
understanding of their use. To that true view of the motion
of blood he was led by a series of steps, each in turn based on
observations made on the heart as seen in the living animal, or
as he himself says * repeated vivisections,* the great step of all
being that one by which he satisfied himself that the quantity
of blood driven out from the heart could not be supplied in any
other way than by a return of the blood from the arterial
endings in the body through the veins. As he himself says :
"Since all things, both argument and ocular demonstration,
" shew that the blood passes through the lungs and heart by
" the action of the ventricles, and is sent for distribution to all
" parts of the body, where it makes its way into the veins and
" pores of the flesh, and flows by the veins from the circum-
"ference on every side to the centre, from the lesser to the
" greater veins, and is by them finally discharged into the vena

n] Circulation of the Blood, 47

" cava and right auricle of the heart, and this in such a quantity
" or in such a flux and reflux thither by the arteries, hither by
" the veins, as cannot possibly be supplied by t*he ingesta, and
" is much greater than can be required for mere purposes of
"nutrition; it is absolutely necessary to conclude that the
" blood in the animaFs body is impelled in a circle, and is in a
"state of ceaseless motion; that this is the act or function
" which the heart performs by means of its pulse ; and that it
" is the sole and only end of the motion and contraction of the
" heart."

Harvey's argument is essentially a physical mechanical
argument ; the problem which he puts before himself to solve
is essentially a mechanical physical problem ; the solution of that
problem at which he arrived is essentially a mechanical solution
of the phenomena of the circulation. As we have seen, in the
minds of those before him the mechanical problems of the
circulation were mixed up with questions about the distribution
of the various kinds of spirits, the natural, vital and animal
spirits. With these questions Harvey does not deal at all. In
an early passage he says, " Whether or not the heart, besides
** propelling the blood giving it motion locally and distributing
"it to the body, adds anything else to it — heat, spirit, per-
" fection, — must be inquired into by and by, and decided upon
" other grounds." And never again, throughout the whole of
his argument, does he refer to the questions of the spirits.

Yet his demonstration was the death-blow to the doctrine
of the * spirits.* The names it is true survived for long after-
wards, but the names were henceforward devoid of any really
essential meaning. For the view of the natural and vital
spirits was based on the supposed double supply of blood to all
the tissues of the body, the supply by the veins carrying natural
spirits and the supply by the arterial carrying vital spirits.
The essential feature of Harvey's new view was that the blood
through the body was the same blood, coursing again and again
through the body, passing from arteries to veins in the tissues,
and from veins to arteries through the lungs, heart, sufiering
changes in the substance and pores of the tissues, changes
in the substance and pores of the lungs.

48 Harvey and the [lbct.

The new theory of the circulation made for the first time
possible true conceptions of the nutrition of the body, it cleared
the way for the chemical appreciation of the uses of blood, it
aflforded a basis which had not existed before for an under-
standing of how the life of any part, its continued existence
and its power to do what it has to do in the body, is carried
on by the help of the blood. And in this perhaps, more than
its being a true explanation of the special problem of the heart
and the blood vessels, lies its vast importance.

We shall see presently how the new way thus opened up
by Harvey was followed with brilliant success, on the one hand
in England, and on the other hand in Italy. Meanwhile it
may be well to turn aside to tell in a brief way the story of
a special but yet important addition to our knowledge of the
blood system, which was being made at the very time that
Harvey was meditating over and developing his views.

That the food which disappears from the alimentary canal,
during its passage along it, becomes in some way or other
blood, was a view which took origin in the early days of
mankind so soon as man began to consider what took place
within his frame. It was part of the Galenic doctrine that
the foocl thus utilized for the body, was taken up from the
alimentary canal by the vena porta, and carried to the liver
there to be enriched with the natural spirits and so concocted
into the blood which passed on to the heart.

Galen himself quotes Erasistratus as having seen that, in
young kids which had lately sucked, the arteries in the
mesentery contained milk, and indeed had observed the same
thing himself. Eustachius too, the anatomist of Rome, who
flourished between Vesalius and Fabricius, whose name and
labours are preserved among us by the Eustachian tube and
Eustachian valve, saw apparently what we now call the thoracic
duct. Nevertheless it may be said that up to the early years
of the seventeenth century, anatomists were aware of one set
of vessels only, the blood vessels, arterial or venous.

In the year 1622 Gaspar Aselli of Cremona, Professor of
Anatomy at Pavia, discovered the lacteals; and this is how
he relates his discovery :

n] Circulation of the Blood. 49

"On the 23rd of July of that year (1622) I had taken a

"dog in good condition and well fed, for a vivisection at the

" request of some of my friends, who very much wished to see

" the recurrent nerves. When I had finished this demonstra-

" tion of the nerves, it seemed good to watch the movements

"of the diaphragm in the same dog, at the same operation.

"While I was attempting this, and for that purpose had

"opened the abdomen and was pulling down with my hand

"the intestines and stomach gathered together into a mass,

"I suddenly beheld a great number of cords as it were,

"exceedingly thin and beautifully white, scattered over the

"whole of the mesentery and the intestine, and starting from

"almost innumerable beginnings. At first I did not delay,

" thinking them to be nerves. But presently I saw that I was

" mistaken in this since I noticed that the nerves belonging to

"the intestine were distinct from these cords, and wholly

"unlike them, and, besides, were distributed quite separately

"from them. Wherefore struck by the novelty of the thing,

" I stood for some time silent while there came into my mind

" the various disputes, rich in personal quarrels no less than in

" words, taking place among anatomists concerning the mesaraic

" veins and their function. And by chance it happened that a

" few days before I had looked into a little book by Johannes

"Costaeus written about this very matter. When I gathered

" my wits together for the sake of the experiment, having laid

" hold of a very sharp scalpel, I pricked one of those cords and

" indeed one of the largest of them. I had hardly touched it,

" when I saw a white liquid like milk or cream forthwith gush out.

" Seeing this, I could hardly restrain my delight, and turning

"to those who were standing by, to Alexander Tadinus, and

" more particularly to Senator Septalius, who was both a member

" of the great College of the Order of Physicians and, while I am

" writing this, the Medical officer of Health,* Eureka' I exclaimed

" with Archimedes, and at the same time invited them to the

"interesting spectacle of such an unusual phenomenon. And

" they indeed were much struck with the novelty of the thing."

Aselli detected the presence of valves in these vessels and

recognised that they hindered the backward flow. He saw

F. L. 4

50 Harvey and the [lect*

clearly indeed that his newly discovered vessels were channels
for conveying the chyle, the elaborated contents of the in-
testine, away from the intestine ; but influenced doubtless by
the accepted view that all the absorbed food must be carried to
the liver to be there elaborated into blood, he went wrong as
to the ultimate course taken by these vessels ; he could trace
them he thought into the liver. It may here be noted in
passing that Aselli in his treatise speaks of and indeed figures
the cluster of lymphatic glands lying in the mesentery as *the
pancreas*; and this cluster of glands was afterwards often
spoken of as * the pancreas of Aselli/

Aselli's discovery by itself was not perhaps of capital
importance ; and indeed for a quarter of a century it remained
an isolated and barren bit of knowledge. After that interval,
however, Jean Pecquet, a French physician who practised first
in Dieppe and subsequently in Paris, in his Experimenta
nova anatomica, published in Paris in 1651, made known
a further discovery, one which he says he had come upon years
before while studying at Montpellier, the discovery of the
receptacle of the chyle and its continuation as the thoracic
duct. Pecquet not only accurately describes these structures,
but shews that on the one hand Aselli's lacteals pour their
contents into the receptacle, and that on the other the thoracic
duct, the continuation of the receptacle, pours its contents into
the venous system at the junction of the jugular and sub-
clavian veins. In the following year, 1652, Van Horn made
known the same discovery, which he appears to have arrived at
quite independently of Pecquet.

By this discovery of the thoracic duct and its entrance into
the veins, a wholly new aspect was given to Aselli's original
observation. The mere existence of special vessels such as the
lacteals in the mesentery was quite consistent with, indeed
supported, the old views of the circulation. Pecquet's observa-
tion was wholly inconsistent with them; but between Aselli
and Pecquet, Harvey's book had appeared; and it may be
taken as a proof of how profoundly Harvey's arguments tad
in so short a time influenced men's minds, that Pecquet s
observations, which if put forward thirty years before would

n] Circulation of the Blood. 51

have been rejected as impossible, were now accepted without
misgivings. Indeed they afforded no little support to the new
theory of the circulation.

Further support was supplied almost at the same time by
the publication in 1653 of the Nova ewercitatio anutomica of
Glaus Rudbeck, Professor of Anatomy and also of Botany in
the University of Upsala (after whom is named the genus
Rudbeckia). In this treatise Rudbeck described under the
name of vasa serosa or aquosa, or ductus serosi, aquosi, vessels
like the lacteals in structure, but containing not milk, or chyle,
but a clear watery liquid, vessels which we now call lymphatics.
He saw them first in the liver and intestines and traced them
to the thoracic duct, of whose existence, he says, he became
aware in 1650 before the publication of Pecquet's book. We
learn from Glisson that one Jolive, an Englishman, in taking
his Doctors degree at Cambridge in 1652, presented in his
thesis an account of these same lymphatics, and by some
authors priority in the matter is thereby claimed for him.

Within a few years then of the publication of Harvey's
book, anatomists became aware of a new set of vessels, of whose
existence no one before had dreamed, vessels neither arteries
nor veins, vessels containing not blood but either a milky or a
clear limpid fluid, and carrying their contents not to but away
from the tissues, carrying them moreover not to that great
organ the liver, which in the old view was the chief seat of all
concoction, but directly into the venous blood stream and so
to the heart, from thence to be distributed all over the body.
That such a conception almost at once found general accept-
ance is, as we have just said, a striking proof of how rapidly
and profoundly Harvey's work had influenced the views of
physiologists.

When Aselli first discovered his lacteals he very naturally
concluded that all the chyle, the whole of the nutritive and
absorbable contents of the alimentary canal, found its way into
the system through them. It is interesting to note that Harvey
hesitated to accept this conclusion. In a letter to Morison
at Paris written in April 1652, a year after the publication of
Pecquet's treatise, he says,

4—2

52 Harvey and the [lect.

" With regard to the lacteal veins discovered by Aselli, and
"by the further diligence of Pecquet, who discovered the
"receptacle or reservoir of the chyle, and traced the canals
" thence to the subclavian veins, I shall tell you freely, since
"you ask me what I think of them. I had already in the
" course of my dissections, I venture to say even before Aselli

"had published his book, observed these white canals, But

" for various reasons, and led by several experiments, I could
" never be brought to believe that that milky fluid was chyle
"conducted hither from the intestines, and distributed to all
"parts of the body for their nourishment; but that it was
" rather met with occasionally and by accident, and proceeded
" from too ample a supply of nourishment and a peculiar vigour
" of concoction/'

And he goes on to argue against the probability of all the
material' solid and liquid absorbed from the alimentary canal,
taking this path of the lacteals only. " Why indeed should we
"not as well believe that the chyle (digested contents of the
" intestine) enters the mouth of the mesenteric veins and in
" this way becomes immediately mingled with the blood where

"it might receive digestion and perfection And that the

" thing is so in fact, I find an argument in the distribution of
" innumerable arteries and veins to the intestines, more than to
" any other part of the body, in the same way as the uterus
" abounds with blood vessels during the period of pregnancy."

With Harvey's demonstration of the circulation of the blood,
supplemented as it was with the discovery of the lymphatics,
physiology was almost suddenly transformed. Harvey's work
had a double effect. In the first place it rendered possible an
exact inquiry into the properties and functions of the organs and
tissues of the body. So long as the blood in the arteries and in
the veins were looked upon as two different kinds of waves as it
were, breaking upon and ebbing from the tissues, the one carry-
ing vital, and the other natural spirits, there seemed to be no
opening for any attempts to explain the phenomena exhibited
by this or that part, this or that organ or tissue on physical or
mechanical principles; everything was wrapped up in the
mystery of the spirits. So soon however as it was recognized

n] Circulatio7i of the Blood. 53

that the blood which was carried to a part along the arteries
came back away from the part along the veins, the same blood,
altered it might be in the tmnsit but still the same blood,
such attempts became at once possible. The spirits became at
once mere qualities of the blood, their names might be retained,
but the virtue had gone out of the names ; the names were no
longer a hindrance to exact inquiry as to what took place in an
organ when it entered into a phase of activity and how that
activity was influenced by or influenced the blood.

In the second place Harvey's work was a shining example
for all future inquirers. The patient examination of anatomical
features, if possible a comparison of those features in the same
organ or part in more animals than one, the laying hold of some
explanation of the purpose of those features suggested by the
features themselves, and the devising of experiments, by vivi-
section or otherwise, which should test the validity of that
explanation, that was Harvey's threefold method. It had it is
true been followed before, by Vesalius and succeeding anatomists,
and indeed in a measure by Galen himself; but these had for
the most part been content with the explanation suggested by
structure, and had rarely used the test of experiment, though
as we have seen Vesalius at least saw its value. It was
Harvey's great merit to have boldly used the experimental
method, to have set a lesson, to the zealous following of which
the progress of physiology after him has been largely due.

All great men have their detractors ; and Harvey has been
no exception. Many writers have attempted to claim for others
than him the credit of his great work. To Servetus, Realdus
Columbus and Caesalpinus and to others has been attributed in
turn the merit of the discovery of circulation. I trust I have
been able to put in a clear light what were the several con-
tributions to the progress of knowledge of the above three men,
and how wholly they fell short of Harvey. I need not tarry to
speak of Carlo Ruini of Bologna, who, though no professor,
wrote in 1598 a very admirable book on the Anatomy of the
Horse, in which he shewed that he had grasped, in a striking
manner, the actions of the valves of the heart. One name
however needs to be dealt with, that of Petrus Paulus Sarpi,

54 Harvey and the Circnlation. [lect. n

the brilliant Venetian, theologian, philosopher, and martyr.
Sarpi studied anatomy as indeed he studied all the sciences of
his time, and he studied it under Fabricius. Now, one Thomas
Cornelius Consentinus is the author of the story that Sarpi,
while he was studjdng at Padua arrived at conclusions con-
cerning the circulation of the blood identical with those of
Harvey, conclusions developed in a manuscript found among
his papers after his death. The story goes on to say that Sarpi
had made known his conclusions to his master Fabricius, who
did not himself think much of them, but told his pupil Harvey
about them ; and Harvey going home to England published
them as his own.

But Ent in his Apologia gives a very different version.
He says that the Venetian Legate returning from London to
Venice carried with him a copy of Harvey's book, which had
just appeared. This copy he lent to Sarpi, and the latter was
so struck with the new views that he transcribed for his own
use very much of the lent book. It was this transcription of
Harvey which Sarpi's heirs found among his papers after his
death.

All such attempts to take away from Harvey what is his
due are vain and useless efforts. The greatness of all great
men is partly built on the worth of those who have gone before.
In science no man's results are wholly his own, like other living
things they come from something which lived before. Vesalius,
Servetus, Fabricius and the rest led up to Harvey; but they
were not Harvey. He was himself, and his greatness is in no
wise lessened by its having come through them.

LECTURE III

BORELLI AND THE INFLUENCE OF THE
NEW PHYSICS.

Harvey's method of inquiry was that which may be called
the purely or strictly physiological method. Observing care-
fully the phenomena of the living body, he sought in the first
place, in the arrangements of the structures concerned in the
facts of anatomy, for suggestions as to how the phenomena
might be explained. It is this aspect of his method which
brings into striking light the value of the work of Vesalius and
of the school of Vesalius as the necessary preparation for
Harvey's labours. Vesalius opened up the way for physio-
logical inquiry by his exact anatomical labours, but as we have
seen left the physiological plough almost as soon as he had put
his hand to it. And his successors did little more than widen
the way which he had opened up. Harvey was the first who
followed up the anatomical path till it led to a great physio-
logical truth.

Having made sure of the anatomical facts and having grasped
the suggestions which these oifered, he proceeded at once to test
those suggestions by experiments on living animals. It was as
he himself has said through many vivisections that he was led
to truth.

He made no appeal to any knowledge or to any conceptions
outside the facts of anatomy and the results of experiments.
Though few at that time could speak of the processes of living
bodies without bringing in the actions of spirits, natural, vital,

1

56 Borelli and the Influence [lect.

or animal, ever seeking to explain those processes by what the
spirits eflfected, Harvey left these spirits entirely on one side;
as we have seen, in one passage only in his book does he refer
to them, and then simply to dismiss them as irrelevant. ' On
the other hand he in like manner made no appeal, as the so-
called philosophers of his time and of times before had done, to
the general properties of matter, to the phenomena presented
by all things, whether living or not living. There is no
attempt in his book to solve the problems of the living body
by an appeal to what we now call physical and chemical laws.
His work, aBdb.iBBfiunid, is purely and strictly physiological.
— And indeed when Harvey began his studies there was no
exact science of physics or of chemistry to which he could
appeal. There was plenty of philosophising about nature, and as
we shall see, the foundations of chemistry were being laid; but
there was no sound .body of truth, which he could call in to his
help. In one respect the science of living things was at this
epoch ahead of that of things not alive, for the latter had no
such solid basis as was already supplied to the former by
anatomy.

During Harvey's lifetime however, even while he was
labouring at his great work, an important change [in this
respecfWas taking place. During the early part of the seven-
teenth century the science of physics sprang into being, and a
little later %«a^ rational chemistry began to emerge from a
mystic alchemy. No sooner had these two sciences come to
the front, than they were pressed sometimes wisely, sometimes
unwisely into the science of physiology, sometimes wisely, to
the great profit of physiology as an independent science, some-
times unwisely, whereby the school of physiology proper, the
school of Vesalius and Harvey, was split up into the school of
those who proposed to explain all the phenomena of the body
and to cure all its ills on physical and mathematical principles,
the iatro-mathematical or iatro-physical school, and into the
school of those who proposed to explain all the same phenomena
as mere chemical events, the iatro-chemical school.

When Harvey reached Padua in 1598, and conversed as he
doubtless did with members of the University other than those

m] of the New Physics. 57

who were studying, like himself, anatomy and medicine, he
must have heard much of the man who had come to Padua
from Pisa some six years before, and who making use and at
the same time further developing a new method of thought
and a new means of inquiry, which under the name of mathe-
matics had been making great progress in the latter half of the
preceding century, was bringing forth astounding new things,
not only about the sun and the stars, but also about the
working of machines and the fundamental properties of matter.
For Galileo Galilei had in 1592 left his native city Pisa, where
he had already made some of his immortal discoveries, to
become Professor at Padua, where till 1610 he fruitfully
laboured, as yet unharassed, for the blood-hounds of the Church
had not caught scent of the heresies of his teachings.

It is not for me here to dwell on Galileo's labours in
physical science ; but it is important, in the history of physio-
logy, to remember that through his and his fellow labourers*
inquiries, the science of physics made at this epoch a great
bound forward. The influence of that progress made itself
almost immediately felt in the science of living things.

Before I go on however to speak of the definite new
contributions to physiology which may be regarded as the
more or less direct outcome of the new school of exact and
mathematical physical science, I must as it were turn aside to
speak of one who without making so much as one single
physiological discovery wrote a treatise on and expounded a
complete system of physiology. This however he wrote not for
the purpose of advancing physiology in particular, but as a
contribution to a general system of philosophy ; and though by
it physiology gained no immediate new results, indeed much of
the teaching contained in it was retrograde, yet the general
ideas which inspired it influenced physiological thinkers even
of his own time, and still more those of the times which
followed.

Ren6 Descartes, bom near Tours in 1596, and dying at
Stockholm in 1650, makes a great figure in the history of
human thought. He was a great mathematician ; he may be
said to have invented analytical geometry. He was an accom-

58 BoreUi and the Influence [lkct.

plished physicist ; hi« theory of the Universe {Le MondSy 1664)
influenced men's opinions about nature for many a year. Above
all he was a philosopher. His Discours de la Methode, 1637,
made an epoch. But he was neither an anatomist nor a
physiologist ; he studied both anatomy and physiology, but not
as an inquirer. He approached these matters as an amateur,
but as an amateur having a special purpose, as one desirous to
construct out of the current knowledge of the time a physio-
logical basis for his philosophical views.

It was part of his philosophy to shew that man consisted of
an earthly machine (machine de terre) inhabited and governed
by a rational soul {dme raisonnable) ; and under the title of
'Man/ L' Homme (De Homine Liber, 1662), he wrote a treatise
of physiology, not, as I have said, as a contribution to physio-
logical knowledge, but as a popular exposition of the features
of the earthly machine in illustration of its relations to the
rational soul. The work thus stands out as the first Text-Book
of Physiology, written after the modern fashion, though in a
popular way. We may perhaps speak of him as the Herbert
Spencer of the age in so far that his treatise on man bore
somewhat the same relation to the physiological inquiries of
the time as the Principles of Biology do to the biological
researches of the present day.

But Descartes had much more distinctly in view than had
Spencer the object of popular exposition, and he had especially
in view the exposition of the mode of action of the soul. Thus
though he begins with the beginning, namely with the ingestion
of food, he hurries over digestion and also over the circulation.
He was acquainted with Harvey's work, but he had not been
convinced by Harvey's arguments ; he was not familiar enough
with the details of physiological inquiry to feel the full fore©
of Harvey's reasonings. He admitted Harvey's great and new
conclusion, the greater circulation, the passage of blood from the
arteries to the veins, but he would not admit what Harvey
insisted, and truly insisted upon as the keystone of his whole
argument, the propulsion of the blood by the systole, by the
contraction of the heart. He clung in the main to the old
doctrines. This is what he says:

in] of the New Physics. 59

After speaking of the formation of blood in the liver out of
the chyle of the food, he goes on thus,

" Now this blood has one obvious passage only by which it
" can get out, namely that one which carries it into the right
" cavity of the heart ; and you must know that the tissue of the
"heart contains in its pores one of those fires without light
" of which I spoke above, which makes it so hot, so ardent that
" no sooner does the blood enter into one or other of the two
"chambers or cavities which are in the heart, than it imme-
"diately expands and dilates, just as you would find the blood
" or the milk of an animal would do if you were to pour it drop
"by drop into a vessel which was very hot. And the fire
"which exists in the heart of the machine which I am de-
" scribing serves no other purpose than that of expanding, heating
" and as it were subtilizing the blood which falls continually drop
" by drop, through the channel of the vena cava into the cavity
" of its right side, whence it is exhaled into the lung, and from
" the vein of the lung, which the anatomists call the vein-like
" artery, into the cavity of the other side, whence it is distri-
"buted over the whole body.

" The tissue of the lung is so delicate and soft and always
" kept so fresh by the air breathed that so soon as the vapours
"of the blood which pass out from the right cavity of the
" heart enter into the artery which the anatomists call the
" artery-like vein, they are condensed and converted once more
" into blood, and then fall drop by drop into the left cavity of
"the heart, where if they entered without being condensed
"anew they would not be adequate to nourish the fire which
"exists there.

*******

"The pulse or beating of the arteries depends on eleven
"little membranes which like so many little doors open and
" close the openings of the four vessels which open into the two
"cavities of the heart. For at the moment that one of the
"beats ceases and another is ready to begin, the little doors
" attached to the openings of the two arteries are firmly closed
" while those at the openings of the two veins remain open, so
"that two drops of blood cannot help falling by these two

60 Borelli and the Influence [lect.

"veins, one into each cavity of the heart. These drops of
"blood are then rarified, and all of a sudden filling up a space
"incomparably greater than that which they occupied before,
"press upon and close those little doors which guard the
" entrances to the veins, preventing by this means any more
"blood falling into the heart, and press upon and open the
" doors of the two arteries, into which they, the drops of blood,
"enter promptly and with force, thus making the heart and
" with it all the arteries of the body expand. But immediately
"afterwards this rarified blood is condensed once more or
" penetrates into other parts ; and thus the heart and arteries
"cease to be distended, the little doors which guard the en-
" trances to the two arteries close again, and those which guard
" the entrances to the two veins open again and give passage
" to two other drops of blood, which once more make the heart
"and arteries expand, just like those which went before."

Such is Descartes' dogmatic exposition of the working of
the heart. Rejecting Harvey s new conclusions, he takes his
stand on the old Galenic doctrine of the innate heat of the
heart, and of the expansion of the heart by that heat. But
indeed about these things he did not care much ; his mind was
set on the nervous system; he was concerned with the circu-
lation only so far as this supplied the material basis of nervous
energy. He only sought to explain how the blood, itself
derived from the food, gave rise to those animal spirits by means
of which the special earthly machine, the brain with its nerves,
carried out the behests of the rational soul. He thus explains
how the best part of the blood is carried to the brain for the
purpose of generating the animal spirits :

" The most agitated and vivified parts of the blood, being
"carried to the brain by the arteries which spring from the
" heart in the most direct line, constitute as it were a very
"subtle air or wind, called the animal spirits, which dilating
" the brain fit it to receive the impressions of external objects
" and also those of the soul, that is to say, fit it to be the seat
" of common sensation, of imagination, and of memory. This
" air or these spirits then flow from the brain along the nerves
"into all the muscles, whereby they dispose the nerves to

m] of the New Physics. 61

"serve as the organs of the external senses, and finally
"distending the muscles give movement to all the limbs/'

What I have just quoted is enough to shew that Descartes
was not a physiological inquirer. His method in physiology
was not that of Harvey, not that which since Harvey's time has
continued to bring in a rich harvest of discovered truth, not
that of working one's way by careful observation, and patient
experiment or trial, out of exactly determined anatomical facts,
up to the real meaning of the facts. He had a special purpose in
view, and with that in view took a freer, wider sweep. He had
to shew that the new views which were making it clear in so
surprising a way that the universe was a machine working in
accordance with physical laws, might be applied also to man ;
that man, that is to say the body of man, might also be regarded
as a machine working in accordance with physical laws. He
had to shew this with the help of the knowledge of the
time, and he achieved this by picking out such parts of the
anatomical discoveries of the age as suited his purpose, and by
weaving these together with many other statements, for which
he gives no authority and which he yet treats as accredited
truths, into a theory of the constitution and action of the
nervous system viewed as a mere machine.

I shall have occasion in a later lecture to dwell on some of
the details of Descartes' theory of the working of the nervous
system, and to shew how he utilized the doctrine of the animal
spirits to explain the phenomena of sensation and movement.
For him, as we shall see, the animal spirits constituted a fluid,
a very subtle fluid it is true, but still a fluid amenable to the
physical laws governing fluids, and for him the nerves were tubes
along which the spirits flowed in a wholly mechanical manner.
In his exposition he makes assumptions, such as the presence
in the nerves of valvular arrangements, for which he gives no
evidence and for which he had no authority. I do not enter
into these points now, I only wish to call attention to his work
as an attempt to apply the new philosophy of exact mathematics
and physics to the interpretation of the phenomena of living
things.

Descartes' contemporaries stumbled, as we now stumble, at

62 BoreUi and the Infliience [lect.

those parts of the basis of his views for which they could find
no authority given by anatomical observation or by physiological
experiment. Hence his views on the nature of man found no
place in the physiology of the day, they passed over wholly into
philosophy so called. But his main idea, that the problems of
man ought to be treated in the same way as the problems of
the re$t of nature, made itself felt and produced eflfects in after
times.

I cannot do better than quote the words of a remarkable
contemporary of his, one of whom I shall soon have to speak,
Nicolaus Stensen, who in a discourse delivered in Paris on the
anatomy of the brain thus sums up Descartes' position as a
physiologist.

" Descartes," says he, " was too clever in exposing the errors
" of current treatises on man to be willing to undertake the task
" of expounding the true structure of man. Therefore in his
*' essay on Man he does not attempt such a delineation, but is
"content to describe a machine capable of performing all the
" functions of which man is capable. And in this sense we may
"affirm without exaggeration that Descartes bears the palm
"over all other philosophers in this matter. For he was the
"first who dared to explain all the functions of man, and
"especially of the brain, in a mechanical manner. Other
"authors describe man; Descartes puts before us merely a
"machine, but by means of this he very clearly exposed the
" ignorance of others who have treated of man, and opened up
" for us a way by which to investigate the use of other parts of
" the body, though it may be diflScult to do so with the same
" clearness and fidelity with which he proceeds in demonstrating
" the parts of his machine of man, a task which no man before
" him attempted.*'

From this excursion into wider fields we now return to the
narrower one of the eflfects of the teaching of Galileo on the
more special problems of physiology, and this brings us at once
to the labours of BoreUi.

Giovanni Alphonso Borelli was bom at Naples on Jan. 28,
1608, in the Nuovo Castello, where his father, a man of humble
origin, though his mother was of a good family, was serving as

m] of the New Physics. 63

a soldier. Of his early days little or nothing is known, but he
himself tells us that he studied mathematics at Rome under
Benedetto Castello. His great ability was not only at once
obvious to his teacher but soon became known to others; for
while as yet a young man, probably about 1640 or possibly
earlier, he was invited to and accepted the chair of mathematics
at the University of Messina, which was then making itself felt
as an active seat of learning. He, like other mathematicians
of the time, was a pupil of Galileo, in the sense that he had
learnt much from that great man through his writings and
indirectly in other ways. But he had apparently never listened
to his voice, and so earnestly did he desire to do so that with
the consent and indeed at the expense of the University he left
Messina for a while in order to visit Florence and see Galileo.
Unhappily very soon after his arrival in 1642 Galileo died, and
Borelli, though he appears to have stayed some time in Florence
enjoying intercourse with Torricelli, returned to Messina, where
in 1649 he published his first work, an account of the pestilence
raging in Sicily in 1647-8. Though in the first place a
mathematician and a physicist, he like other learned men of
the time busied himself with inquiries reaching outside his
own line; that he was justified in doing so is shewn by
the fiict that in this treatise he attacked the views held of
physicians concerning the cause of the disease, and contended
that it was due to what we should now call an air-borne
germ.

His fame while at Messina grew so great and spread so far
that in 1656 he was invited by Ferdinand Duke of Tuscany to
fill the chair of mathematics in the University of Pisa. The
oflforts of the Medici to make their university an academic
power were being crowned with success, and Pisa was now
outshining Padua. Borelli accepted the invitation, and so
began what was perhaps the brightest and the best part of
bis career, though he was already forty-eight years. old.

Much as he owed to his chief teacher Castello, Borelli was
to a large extent a self-taught man. He seems not to have
paid much attention to literary studies, and his life at Messina
was probably more or less a provincial life, a life marked with

64 BoreUi and the InfltLence [lect.

provincial characters. Coming to Pisa he was plunged at once
into the most polished life of the times. And there is a story
that at the introductory lecture which against his will he was
induced to give upon entering into oflSce, his clumsy diction,
his rude gestures, his long-winded and yet halting sentences
were so little to the taste of his fastidious audience that they
broke out into derisive laughter and brought the lecture to a
premature close.

In spite of this Borelli soon made his power felt. Though
his chief duty was to teach mathematics, he threw himself with
zeal also into other kinds of learning. Malpighi, as we shall
presently see, came from Bologna to Pisa at the close of the
year of Borelli's arrival. The two at once became close friends,
and anatomy soon occupied Borelli*s energies almost as much
as mathematics and physics. By his talents and energy he
made the university of Pisa famous as a school for both mathe-
matical and medical science, and his efforts in these directions
were generously supported by the munificence of the Medici.
It was perhaps chiefly through Borelli's unwearied activity in
advancing by way of experiment natural knowledge of all kinds
that in 1657, under the patronage of Prince Leopold, the famous
Academia del Cimento, one of the first of learned societies,
was instituted. Borelli, Malpighi, and the sagacious naturalist
Redi formed a trio which would have been an ornament to any
academy. But the Cimento was not all union. Bt»relli's in-
tellectual gifts lacked the support of an amiable character ; he
was morose and quarrelsome, tenacious of his own right, not
unenvious of the success of others, and apt when contradicted
or opposed to fly into a passion ; some of his contemporaries
speak of him as almost unbearable. He was more than once
led into a quarrel with his colleagues of the Academy, and
eventually became estranged even from Malpighi, who looked
upon him as a father, and who while they were at Pisa together
sought counsel of him almost every day.

During these years Borelli published not only mathematical
works, such as his Euclides restitutus, and astronomical works,
for at Florence during the summer when freed from the duty
of lecturing he under the patronage of the Medici made

in] of the New Physics. 65

observations on the heavens, but also his important physical
work, De vi percussionis. But what he set his mind chiefly to
do was to write a treatise on animal motion, De motu animalium,
embodying the results of the anatomical and physiological
inquiries in which he had been so long engaged, and to the
prosecution of which he had so fruitfully stimulated others.
Although the work was not to see the light for many years,
much of it apparently was written before he left Pisa.

For he did leave Pisa. It seems strange that he should
desire to leave such a centre of light to live once more in an
out of the way and provincial seat of learning. He pleaded as
his reasons the ungenial climate of Pisa and the desire for
more leisure and quiet; others thought it was his inconstant
temper and his repeated quarrels with his colleagues that led
him, in 1668, after twelve years' stay at Pisa to accept an
invitation to return to his old University at Messina. Here if
he had more leisure, his intellectual activity at least in spite of
his increasing years shewed no signs of being on the wane.
He published his important treatise on 'The natural move-
ments depending on gravity,* he investigated an eruption of
Etna, he busied himself in literary and antiquarian studies,
and all the while he continued working on what he felt to be
his great effort, the treatise on animal motion.

In 1674, being concerned, or being suspected of being
concerned, in a political conspiracy to free Sicily from the rule
of Spain, he left Messina for the last time and fled an exile to
Rome. There was at that time living in Rome that remarkable,
I ought perhaps to say notorious woman Christina (daughter of
Gustavus Adolphus of Sweden), who after bearing the burdens
of the crown for ten years (for at her father's death in 1644 she
succeeded to the throne) threw them on one side in 1654, in
order that, free from political cares, she might devote herself to
the charms of travel and of intellectual culture, and to other
pleasures of private life. She, playing the part of Lady
Bountiful in science, held a little academy of her own, and
when Borelli, a needy, or well-nigh needy exile arrived at Rome,
she took him under her protection. He earned the assistance
which she gave him by acting as her physician and also by
p. L. 5

66 Boretti and the Influefnce [lect.

frequently delivering discourses at her academy, discourses
which however he did not think worthy of being published.
For three years he continued thus under her patronage, though
living in his own house on the slender means which he
still retained and on the help which she gave him. He kept
on labouring at his book on animal motion, the expenses of the
publication of which Christina undertook to defray; and in
1676 the work was so near completion that Borelli felt justified
in writing the dedication to her.

The pecuniary aid which Borelli received from Queen
Christina was somewhat uncertain, owing to the fitful way in
which her remittances arrived from Sweden. In 1677 a heavy
blow fell upon him ; his private servant robbed him of all his
little money, and indeed all his property ; and need led him to
take up his abode among the Society of the Scholse Pise of San
Pantaleone, where he dwelt for two years, giving the penultimate
touches to his great work, which as he said he had promised to
the world twenty-four years before, and earning his board and
lodging by teaching mathematics to the young scholars of the
society. The last touches which were needed he did not live
to give ; before the book had left the press he was seized with
a pleurisy, and on the last day of 1679, just as the new year
was coming in, he passed away. The pupil of Galileo, like his
master, bowed before the power of the Church, and an ecclesiastic
dignitary, writing the preface to the work of Borelli, published
the year after his death, breaks out into praises of the pious
life of the great man of science, especially commending him in
that when in his lectures on astronomy he had to speak of
' systems ' he maintained the authority of the Church. '* What-
" ever others may have taught, it is our duty, he used to say,
" not to listen to it. As the Holy Church teaches so ought we
" to believe, and obeying her, to hold as true whatever she lays
"down."

Borelli was essentially a mathematician and a physicist ; of
his valuable contributions to these sciences this is not the place
to speak. The problems of the living body were not to him,
as they had been to Vesalius and Harvey, the object of a first
love. Their care had been to find an answer to the biological

m] of the New Physics. 67

question; and they used all other knowledge as a means to
this end. He, on the other hand, regarded the phenomena
presented by living beings as a field yielding him abundant
opportunities for applying the new methods of physical research.
And we cannot wonder that from this point of view the
movements of animals early attracted his attention. As we
have just said, his gi'eat work, De motu animaliuniy was not
published until after his death, the first volume appearing in
1680, the second in 1681 ; but as we have also said, what is
printed in them had been taught publicly long before, while he
was as yet professor in Pisa; and indeed much of the work
must have been already in manuscript in those early years, for
his pupil Bellini, writing in 1662, refers to it as already a book.

He himself makes quite clear his own opinion of the real
nature of his book. In the introduction he speaks of physiology,
a word which employed rarely in earlier times, by Aselli for
instance, was now coming into general use as a 'part of
physics,' and this he proposes *to ornament and enrich by
mathematical demonstrations.*

Animal movements naturally divide themselves into ex-
ternal movements, such as those eflfected by the skeletal
muscles, and internal movements, such as the movements of
the heart and of other viscera, and in general the movements
of the fluid parts of the body. Borelli treats of each. We will
consider the external movements first.

The various movements effected by the muscles present
two classes of problems : the special problems, mechanical in
nature, of the movements effected by particular muscles ; and
the more general problem, in a certain sense also a physical
one, how the substance of a muscle gives rise to movement, by
what changes in a muscle movement is brought about.

A large part of Borelli's work is devoted to the special
mechanical problems. Vesalius, and later on Fabricius, had
treated of these problems in some detail, but they had treated
of them in a more or less loose way only. They lacked, Vesalius
wholly, and Fabricius to a less but still to a great extent, the
exact mathematical and mechanical knowledge which springing
up in the latter part of the sixteenth century made such rapid

5—2

68 Bordli and the Influence [lect.

progress in the beginning of the seventeenth century under
Galileo and his school. Borelli was of that school, and having
laid a foundation in a chapter entitled, 'Mechanical propositions
useful for the more exact determination of the motive power
of muscles,* he treats in succession of the various problems
of muscular mechanics, of flexion and extension, and of the
more complex problems of standing, walking, running, and
other forms of locomotion ; he investigates these in the same
rigid, exact manner, calling in the aid of mathematical figures
and calculations, as he and others had investigated the problems
of falling bodies, and of the action of various propulsive and
other machines.

One has only to compare the chapters of Fabricius with
those of Borelli which deal with any one of these problems,
that of walking for instance, in order to realize what a large
bound forward mechanical science had made in the first
years of the seventeenth century.

Borelli's discussions concerning these special problems may
be read with profit even at the present day; they supply the
basis of muscular mechanics, and interspersed among them will
be found shrewd observations, which pass from mere mechanics
into more distinctly physiological questions, such for instance
as that in which he calls attention to the distinction between
the weak tonic contraction which a muscle may exercise against
an antagonist muscle, and the more powerful voluntary con-
traction, by which the same muscle does work equivalent to
raising a heavy weight.

Not content with the solution of these problems of muscular
mechanics, problems which could be solved by the almost
direct application of known mechanical methods, and which
called for little special research beyond the mere determination
of the necessary data, Borelli passes on to the more general,
more distinctly physiological, far more difficult question of the
nature of muscular movement ; this also he attempts to solve
by the mechanical mathematical method.

It was recognized of old that the movements of the limbs
and of the various parts of the body were brought about by the
shortening of the structures called muscles. It was also

m] of the New Physics. 69

recognized that nerves were concerned in the action, it being
generally supposed that animal spirits passing along the nerves
to the muscle, provoked in some way or other the movement.
In the muscle itself two parts were recognized : the fibres of
the muscle which, though possessing a nature of their own,
passed into and were continuous with the fibres of the tendon
at each end, and the flesh, ' caro/ which filled up the interstices
between the fibres and adapted itself to them, but which
otherwise was comparable with the flesh, ' caro,' or parenchyma
of other organs, such for instance as the liver. According at least
to general opinion, the contraction, that is the shortening and
hardening of the muscle as a whole, was carried out not by the
flesh, * caro,' but by the fibres of the muscle, the power of the
fibres to effect this being due to the animal spirits reaching
them along the nerves.

Vesalius, passing lightly over this, as over other problems
distinctly physiological rather than anatomical, and this as we
have seen was his wont, has little to say about it, but that
little goes straight to the root of the matter. He saw clearly
that the contractile power of the muscle resides in the actual
muscular substance, not in the fibres of the ligament or tendon
which spread out into the muscle's belly, nor in the nerves
distributed in it, though these played their part as carriers of
the animal spirits. This is what he says:

"Muscle therefore, which is the instrument of voluntary
"movement as the eye is the instrument of vision and the
" tongue of taste, is composed of the substance of the ligament
" or tendon divided into a great number of fibres and of flesh
" containing and embracing these fibres. It also receives
"branches of arteries, veins and nerves, and by reason of
"the presence of the nerves is never destitute of animal
"spirits so long as the animal is sound and well. Now I
"do not regard this flesh as merely a foundation or basis,
"as it were a bed or support by which the fibres and the
"above-mentioned divisions of the nerves are held together.
"Nor do I with Plato and Aristotle (who did not at all
"understand the nature of muscle) attribute to the flesh so
" slight a duty as to serve, after the fashion of fat or grease

70 BoreUi and the Influence [lect.

" or some sort of clothing, the purpose of lessening the effects
" of heat in summer and of cold in winter. On the contrary,
" I am persuaded that the flesh of muscles which is different
" from everything else in the whole body, is the chief agent,
"by aid of which (the nerves, the messengers of the animal
" spirits not being wanting) the muscle becomes thicker, shortens
" and gathers itself together, and so draws to itself and moves
"the part to which it is attached, and by help of which it again
"relaxes and extends, and so lets go again the part which it
"had so drawn. It is clear that the proper substance of an
" organ is the agent of the primary functions of the organ, as
" is the case in the brain, heart, liver, lungs, spleen, kidney and
"testes."

Fabricius discourses in three long rambling chapters on
the structure, the action, and the uses of muscle. In these he
shews here and there the influence of new ideal, as for instance
when he compares the action of a nerve in inducing muscular
contraction, though itself not contracting, to that of a magnet
which causes a piece of iron to move, though not itself moving.
Yet his teaching is on the whole the old teaching that the
contractile power resides in the fibres of the muscle, not in the
flesh. So far from advancing beyond Vesalius, he falls behind
him; in this as in other matters Galen is his master, not Vesalius.
Indeed when Borelli attacked the problem, this was very much
where Vesalius had left it, for Descartes had passed it lightly
over.

He had the advantage of being able to start with a truer
knowledge of the minute structure of muscle. As we shall see
in the succeeding lecture the microscope had about this time
come to the aid of the anatomist, and Malpighi, Borelli's friend'
and colleague at Pisa, was using the new aid as a means of
achieving brilliant discoveries concerning the finer structure of
living beings. Nor was the new instrument being used by
anatomists at Pisa only. Before Borelli's book was published,
but, probably, not before he had written or at least begun
to write it, there appeared in 1664 a little tract, De musculis
observationum specimen, expanded, and illustrated with figures
a few years later in 1667 as Elementorum myologiae specimen.

m] of the New Physics. 71

written by a Dane, Nicolas Stensen, better known perhaps by
his Latin name of Steno, to whom I have already referred and
of whom I will venture to say something more in detail in a
succeeding lecture. Stensen had used the microscope and had
been led to the following conception of the structure of a
muscle.

According to him a muscle is essentially a collection of
motor fibres. Each motor fibre (fibra motrix), itself a complex
of most minute fibrils, arranged lengthways, has a middle
part, which differs in consistency, thickness and colour from
each of the ends. The several motor fibres are bound together
by the continuous transverse fibrillae of the proper membrane
of the muscle. The middle parts of the motor fibres, wrapped
round by the membranous fibrillse, constitute together the
fleshy part of the muscle, which soft, broad and thick differs
in colour in diflferent animals, being reddish or pale or even
whitish ; in the leg of the rabbit you will find some muscles
red and others pale. The end parts of the motor fibres, which
are always white, thin, and tough, constitute together the
tendons. It is the fleshy parts of the motor fibres and these
alone which contract, and in doing so become shorter, harder,
and corrugated on the surface; the tendinous parts remain
unchanged.

It will be seen that Stensen had come very near to a
true conception of the structure of muscle. What he called
a 'motor fibre' we now call a * fasciculus,* his 'most minute
fibrir is our 'elementary fibre,' and we speak of his 'proper
membrane ' with its transverse fibrillse as * the connective tissue
fi:ttmework.' Stensen too like Borelli was full of the new
spirit of the mechanical philosophy of the day ; and the greater
part of the work of which I am speaking is taken up with
elaborate mathematical mechanical expositions. In a muscle,
says Stensen, the middle fleshy part is an oblique angled
parallelepiped, and the tendon at each end is a tetragonal
prism ; and he develops at length the geometrical consequences
of this conception.

Borelli was acquainted with Stensen's work, he accepts his
exposition of the structure of muscle, and speaks of muscular

72 Borelli and the Influence [lbct.

fibres and muscular fasciculi as the real contractile part, the
fibres of the tendon serving only to bind the fleshy fibres to
bones or other structures. It is true that he refutes Stensen's
mathematical mechanical conceptions of the arrangement of
the fibres, replacing them by conceptions of his own ; but this
is a matter of little moment. Both observers had grasped the
all important fundamental fact that the act of contraction is
carried out by the fleshy muscular fibre and that the fibres of
the tendon, howsoever far they may seem to enter the muscle,
are mere passive agents, retaining their normal length and
consistence and taking no part whatever in the contraction.
The old idea of the contractile tendinous fibres, and of the flesh
*caro,' serving the purpose of mere packing was done away
for ever, and Vesalius was justified of his children.

Coming then to the actual nature of this contraction of
the fleshy part, Borelli strove very hard to reach a definite
mechanical explanation of the process. In this he, in one
respect, went distinctly astmy. Recognizing the beat of the
heart as a contraction of the muscular ventricles, and im-
pressed with the fact that, during the systole the walls of
the ventricles closing in laterally obliterate the cavities from
which the blood has been driven, he concluded that the
muscular walls in contracting increase in bulk; and he ex-
tended this conclusion to all muscles. This view of an
increase in bulk led him to suppose that the hardening and
tension observable when a muscle contracts is due, not to
mere displacement of the parts of the muscle itself, but to
an inflation of the muscular substance by something firom
without. And in accordance with this he constructs a hypo-
thesis, in which the muscular fibres are supposed to be chains
of rhombs, and proceeds to shew how contraction, with its
attendant hardening and extension, may be explained by
considering inflation as being the sudden insertion of a number
of wedges.

Having reached this mechanical conception of the act of
contraction itself, he attempts to gain a like mechanical
conception of the way in which the nerves act as the exciting
agents of this contraction. He begins his discussion of the

m] of the New Physics. 73

subject by refuting the wrong explanations of muscular con-
traction which had been put forward by various authors.

"Although Nature is admirable in all her operations yet
** there is no one who is not in the highest degree astounded
*' when he considers the immense force and energy of muscles,
** and sets about to understand more exactly the causes, organs
"and apparatus by which Nature carries out such a work.
" And for the reason that human stupidity is more easily struck
"with the ugliness of error than with the beauty of truth,
" I shall first proceed to expose wrong views, both because this
"part of science is not to be despised, and also because the
" exclusion of what is erroneous the more easily leads us to the
" discovery of what is true."

The first wrong view which he exposes is the one that
muscles are directly moved by some incorporeal agency.

"Muscles do not exercise vital movement otherwise than
" by contracting. Such a violent contraction however is not
"brought about by anything else than the hardening and
" inflation which the muscle undergoes. Now such an inflation
" cannot be conceived without the advent and insinuation of a
" second body. For the corporeal mass of the muscle, possess-
"ing as it does three dimensions, cannot be inflated and
" increased in bulk by any wholly incorporeal influence having
"like an indivisible point no magnitude."

He next refutes the view that muscular movement is
brought about by spirits or by a corporeal air, such as the
atmosphere is.

"There are not wanting those who insist that extremely
" attenuated corporeal animal spirits like air supply the cause of
" the movements of muscles.

"But these cannot extricate themselves from innumerable
" diflSculties. For, according to their views that spirituous air
"either expands the muscles, rushing into their cavities like
" wind, and filling them with its abundance and plenty, or on
" the other hand brings about the contraction by filling up the
" porosities of the muscles through ebullition and rarefaction.
" But this seems to be impossible because the action of a muscle
" is a mere contraction of its length, so that the two ends by

74 Bordli and the Infliisnce [lbct.

"contrary movements are brought towards each other, the
"muscle swelling and enlarging in breadth."

After pointing out the various diflSculties he says, " Finally
" a very common experiment does away with all this nonsense
" about air. When the muscles of a living animal are divided
" lengthwise, while the animal is submerged under water, and in
" consequence of the pain is struggling violently, in the midst
"of such great copious fervour and ebullition of the supposed
" spirituous gas which would thereby be excited in the muscles,
"one would expect that innumerable bubbles of gas would
"burst forth from the wound, and ascend through the water,
"whereas nothing of the kind takes place."

He further goes on to shew that vital contraction cannot
take place by reason of any juice or blood distending the
porosities of the muscles, nor from the blood being driven into
them by the force of the heart.

Having thus discussed the wrong explanations, he proceeds
to expound the probably true explanation of muscular con-
traction.

He concludes that for bringing about muscular contraction
two causes are necessary, one existing in the muscle itself,
the other brought to it from without.

"Since all muscles, with some few exceptions, do not
" manifest vital movement otherwise than in obedience to the
" will, since the commands of the will are not transmitted from
" the brain which is the instrument of the sensitive, and the
" seat of the motive soul, by any other channels than the nerves
" as all confess and as the most decided experiments shew, and
" since the action of any incorporeal agency or of spirituous gases
"must be rejected, it is clear that some corporeal substance
"must be transmitted along the nerves to the muscles or
"else some commotion must be communicated along some
" substance in the nerves, in such a way that a very powerful
" inflation can be brought about in the twinkling of an eye.

"And since the inflation, hardening, and contraction do
" not take place in the channels which serve for bringing them
" about and in which the motor influence resides, namely, in the
" nerves themselves, but takes place outside the nerves, namely.

m] of the New Phydcs. 75

"in the muscles, it is evident that the substance or the
"influence which the nerves transmit is not taken by itself
" alone sufficient to bring about that inflation. It is necessary,
"therefore, that something else must be added, something
"which is to be found in the muscles themselves; or that in
"the muscles there is some adequate disposition of material
"so that on the arrival of the influence transmitted by the
"nerves there takes place something like a fermentation or
"ebullition, by which the sudden inflation of the muscle is
"brought about. That such an action is possible is rendered
" clear by innumerable experiments which are continually being
" made in chemical elaborations as when spirits of vitriol are
"poured on oil of tartar; indeed all acid spirits when mixed
" with fixed salts, at once boil up with a sudden fermentation.
" In like manner therefore, we may suppose that there takes place
" in a muscle a somewhat similar mixing from which a sudden
"fermentation and ebullition results, with the mass of which
"the porosities of the muscle are filled up and enlarged, thus
" bringing about the turgescence and the inflation."

I must not dwell any longer on Borelli's views concerning
muscular contraction. I shall have to take them up again in
connection with the labours of other men on the same subject.
I have said enough to shew how great and rapid an advance
in our knowledge of these matters had been brought about by
the new physical learning. Working on mechanical mathe-
matical lines, and almost on these alone, for it is only at the
end that he calls into his aid some of the chemical ideas which
were beginning to stir men's minds, and his no less than others,
but which were as yet far behind the already current physical
ideas, Borelli was able to approach very near the conception
which was not to be laid hold of for a century or more, the
conception of the irritability of muscle maintained by nutritive
processes, and of the calling that irritability into play by the
advent of nervous impulses.

Borelli had also much to say concerning the internal
movements of the body, movements other than those carried
out by the skeletal muscles. He dwells at length on the
movements of the heart and on the circulation.

76 Borelli and the Influence [lect.

He fully accepts Harvey's views, and developes them in his
own way. Although Harvey could not be ignorant of the
exact mathematical and physical knowledge which was being
gathered up in his time, he as we have seen makes little or no
use of it in his great work. That was based exclusively on the
teachings of anatomy and the results of experiments on living
animals ; he never made use of the new mathematical or even
the new physical methods. This is exactly what Borelli does.
To the physicist the problems of the circulation have always
been fascinating; they obviously were so to Borelli, and he
developes a number of mechanical investigations and specula-
tions. While his brother mathematician Descartes was content
with the old view of the expansion of the ventricles by the
rarefaction and dilatation of the contents through the innate
heat, Borelli seizes the Harveian view of the propulsive power
of the heart in its systole and likens the ventricle to a wine-
press or to a piston. He dwells on the mechanical action of
the spiral arrangement of the fibres of the ventricle, an
arrangement which he says he himself had discovered, though
there is reason to think that the observation is due to Malpighi,
and speaks of the work done by the heart in the following
terms :

" The true action of the muscle of the heart is the contrac-
" tion of its ventricles, and the compression and expression of
" the blood contained in them is carried out after the manner
" of a winepress, and that not by the contortion of the spiral
" fibres of the heart but by their inflation and tension."

He gives the following as the reason why the lateral walls
of the heart are brought together in the systole :

'*A11 the almost innumerable fibres are carried obliquely
"and transversely round the sides of the heart, and form a
"number of strata placed one upon the other like a series of
"membranes. When therefore the fibres of any stratum are
" inflated, these touching each other laterally and lying in one
"plane, naturally push each other sideways, and so mutually
" shove each other out of their proper places, and push each
" other away from their proper situation, namely towards the
" base and the apex. This would tend to increase the interval

m] of the New Physics. 77

"between the base and the apex; but other external fibres;
"surrounding the obliquely transverse ones and intersecting
" them in a decussating manner prevent, as we shall presently
"shew, their elongation and protuberance, whence necessarily
"the inflation of those fibres gives rise to an intumescence
"internally towards the cavities and so the inflated internal
" sides of the walls are brought nearer to each other/'

We have seen that an important link in Harvey's argument
was furnished by his calculations as to the quantity of blood
driven into the arteries from the heart, calculations which were
as we shall see repeated in a more exact manner some years
later by Richard Lower. Borelli goes further, he is anxious to
determine in mechanical terms the force of the ventricular
systole. Assuming that the force of contraction of all healthy
muscular tissue is the same for a unit of bulk, and observing
that the 'fleshy mass of the heart' is in bulk equal to a
masseter and temporal muscle combined, he concludes that
it exercises the same force as these two together, which
force can be determined experimentally. He finds that the
muscles of the two sides of the jaw acting together can support a
weight of more than 300 lbs. The muscles of one side therefore
will support a weight of more than 160 lbs. But this is an
instance of the partial force of a muscle ; if we want to find the
whole force of the muscle we ought to multiply this result at
least 20 times. Thus he reaches the conclusion that the
motive force of the heart considered by itself may be calculated
as equal to that of supporting a weight of more than 3000 lbs.

Perhaps the most interesting part of Borelli's work on
the circulation is his treatment of the flow in the arteries.
Working on the lines of his view that the action of the heart
is to be likened to the action of a piston in a pump, he argues
that at the close of a heart-beat the arteries are not empty,
but still hold a considerable quantity of blood ; according to his
calculations they contain about \ of the total blood of the body,
the quantity introduced at a single beat, namely about three
ounces, being a twentieth part of that, and occupying a space
in the arteries next to the heart not more than half a foot in
length.

78 Borelli and the Influence [lbct.

He discusses at length the resistance which the heart has
to overcome, resistance oflFered by the walls of the arteries them-
selves, by the tissues surrounding them, and by the minute and
variously shaped orifices through which the blood issues from
the terminations of the arteries in the several tissues. And
by a series of mathematical calculations he comes to the con-
clusion that the heart in maintaining the circulation has at each
beat to exert a force equivalent to not less than 135,000 lbs.

His view of the flow in the arteries is worth giving in his
own words:

" In the first place we must disprove the common assertion
"that blood is driven through the terminal orifices of the
"arteries after the fashion of a fountain, simply by the pro-
" pulsive force of the heart.

" The arteries are soft, distensible tubes full of blood, but as
" we have shewn not filled to extreme distension ; and during
" each beat of the heart there is driven into them by the con-
"striction of the heart, acting like a piston, a mass of blood
"suflScient to complete their distension or even more than
"suflScient, in which case the surplus is discharged beyond
" the arteries by the beat of the heart itself. But so soon
"as the beat is over the arteries return from their distended
"condition to the same soft and shrunken state in which they
"were before the beat. Therefore there must have escaped
"from them the mass of blood or the surplus of that mass
" which had been driven into them by the piston of the heart.
" But the blood which has been driven into the arteries cannot
"issue from them of its own accord through the extremely
"minute terminal orifices of the arteries since it possesses no
"force of its own. Nor is it driven out by the propulsion of
" the piston of the heart or only partly so since the arteries are
" not rigid tubes made of steel but are soft, and the force of the
" heart in its direct action is spent in expanding them, which
" expansion acts as a cause of retention rather than of expulsion
"of the blood."

After shewing that the flow of blood out of the arteries
cannot be due to gravity, or to auy force supplied by a
rarefaction of the blood he goes on :

in] of the New Phydcs. 79

" Two eflFects follow the beat of the heart, the filling of the
" arteries with the blood driven into them, and the exit of the
"same blood from the same arteries. Certainly these two
"events cannot take place at the same time; for the one
"consists in an expansion, the other in a constriction of the
"same arteries, and these two being opposed in nature cannot
"take place at the same time. Whence it must be that the
"filling of the arteries takes place first, and that their con-
"striction and emptying follows afterwards.

" The filling and distension however which take place first
"cannot be carried out without a violent extension of the
" transverse fibres of the said arteries. Now we know from other
" sources that all fibres of vessels, and all fibres of muscles, of the
" intestines, of tendons, of membrane, and of the true skin resist
" extension, and when extended possess a power of contracting
" like that of a strung bow. Nay, indeed, we see that all fibres
"when placed in their natural surroundings possess some
"amount of active tension, for when they are divided they
"contract of their own accord and become shorter. This would
"not happen if these fibres existed in a condition of equili-
" brium between extension and contraction ; like the cord of an
"unstrung bow they would suflFer neither contraction nor
" extension.

" But if all fibres in a natural condition undergo some
"amount of extension it follows that, when the arteries are
" filled with blood, the transverse fibres, owing to the enlarge-
" ment of the cavity, must become much more elongated and in
"consequence undergo a much greater extension. And since
"the said expansion of the arteries is succeeded by a con-
" striction which cannot take place without a shortening of the
" circular fibres, and indeed such a shortening is proper to and
"part of the very nature of these fibres, it follows that the
" arteries after their violent expansion, due to their being filled
"to distension, cannot do other than exercise by the law of
"nature that mechanical force which they possess. This
"squeezing the arteries like a rope twisted circularly round
"them expels with force the blood through their terminal
" orifices."

80 BorelM and the Influence [lbct.

This has only to be translated into present language in
order to be read as stating that the steady flow from the
arteries through the capillaries into the veins is the result of
the elastic reactions of the arterial walls, and thus the indirect,
not the direct result of the heart-beat.

Some of Borelli*8 numerical calculations were misleading,
but even in quite recent times numerical calculations of
muscular force based on the latest researches have also proved
misleading, and such miscalculations in nowise lessen the
admiration which one must feel for work shewing, in such
early times after Harvey, such a grip of the problems of
hsemodynamics. We may almost say, even not forgetting
Hales, that Borelli brought our knowledge of the subject
nearly to the point at which after the lapse of more than a
centuiy, indeed of nearly two centuries, Poiseuille and Weber
took it up again.

Borelli completes his treatise on the circulation by con-
siderations on the nature and cause of the heart-beat. In its
immediate nature the heart-beat, the movement of the heart, is
identical with the movement of a limb; both are muscular
contractions of the same order. But the two differ in their
ultimate cause. The movement of the limb is the issue of a
direct action of the will, the movement of the heart is not so.
"It may arise by organic necessity, the heart may move as
" certain automata move. Or possibly the movement may come
"from a voluntary effort of which we have ceased to be
" conscious because it has been repeated so often and so
" constantly/'

After treating the movements of the circulation thus fully,
Borelli goes on to attack by similar methods the problems of
respiration. Of his views on this subject I will not speak
here; it will be convenient to deal with them in another
connection. Nor did he stop at respiration. As we shall see
in the next lecture physiologists were becoming much exercised
in their minds concerning the structure of glands and the
nature of the process of secretion. Borelli attacked these
problems also, and satisfied himself that all the phenomena
of secretion could be explained in a mechanical manner by

in] of the New Physics. 81

the help of hypotheses concerning the size and shape of the
particles to be secreted, and of the orifices or spaces through
which they had to pass. This is what he says :

" For we have shewn that the fluidity of a liquid cannot be
"conceived of without its mass being actually divisible into
" very minute hard and consistent particles of a definite shape,
*' united together not by firm bonds but by simple contact, so
" that some of them can be agitated, can flow, can move about
•'while others are at rest or are moving in another direction.
" In no other way can be preserved that fluidity through which
** fluid parts flow along, mix and fuse together.

" Moreover it cannot be doubted that the different natures
" and properties of fluids depend on the different consistency,
" structure, configuration and motion of the molecules composing
" the fluids. Thus the molecules composing water are all homo-
**geneous and like each other but different from those com-
" posing oil or a fluid of another nature, and indeed it is agreed
" that the particles of the said fluids differ in structure, size
" and shape.

" And indeed if the molecules of two heterogeneous fluids
" were equally mobile so that they could be mixed by simple
"contact, then a mixture of them, a mixture for instance of
" oil and water, might be compared to a mixed heap of millet
"and barley. And since we see that these can be separated
" by a sieve, so in like manner water and oil are able to pass
" through the pores of skin and of wood but air cannot, while
" mercury can pass through the pores of gold but water, oil or
"air cannot. Consequently the said fluids can be separated
" (just as vegetable grains may be) from other different fluids
" with which they may be mixed by means of a sieve of an
" appropriate structure without any fermentation ; for just as
"grains pass through a sieve uninjured, so oil and water can
"pass throut;h the pores of skin or wood, intact, without any
"change. Wherefore it must be confessed that it follows by
" mechanical laws that the reason why fluids of the one kind
" do pass through and those of another kind do not is without
" doubt because the shapes of the molecules of the said fluids
"match and are fitted to the shapes of the minute pores

p. L. 6

82 BoreUi and the Influence [lect.

"through which they are able to pass while the particles of
" another fluid, since their shapes do not match, are excluded."

And dwelling on the secretion of urine he concludes :

" Who then would wish to think that the particles of the
" blood are picked out, separated from the watery particles (of
" the urine) and placed in separate receptacles by some magnetic
** virtue or by some ferment, acting lik^ a servant possessing
"eyes? Certainly unless we wish to lay hold of follies and
" wonders we are bound to confess that (in the kidneys) there
"exist two kinds of orifices after the manner of two sieves,
" namely, one a venous one, which by reason of its adjusted
" configuration receives the particles of blood only, not those of
" the watery urine, and another, the proper vessels of the kidneys,
" the shapes of which are fitted for absorbing the particles of
" water but not the particles of the blood."

With the history of the physiology of secretion I propose
to deal in a general way presently, and will therefore content
myself with thus much of Borelli's views. But I must say one
word about his views of the physiology of nerves, though to
these also I shall have to return later on.

The animal spirits of the older writers become in his hands
a nervous fluid, a fluid subtle and active but still a fluid subject
to the physical laws of fluid, which he calls succus nerveiLS.
He further distinguishes between a succus nerveus nutritivus
and a succus nerveus spirituosus. The former governs the
nutritive processes of the body, it is through these that nerves
exert what we now call a trophic action, the blood suppljdng
material, the nerves the vivifying and plastic force.

The succus spirituosus is concerned in the production of
movements and sensations, it is a fluid subject as we just now
said to physical laws. He developes his views as to the
mechanical arrangements which determine its flow along the
nerves, and in one place compares a nerve to a rod of elder-pith
filled with fluid and so through the fluid capable of transmitting
oscillations. And throughout he insists that the nervous fluid,
the succus nerveus, is essentially a physical fluid. Such a fluid,
says he, be it as spiritual, as subtle, and as active as you please
is always corporeal and is incapable of acting at a distance.

m] of the New Physics. 83

He also discussed in the same spirit the succus spiritttosus
seminalis (Auber, under his supervision discovered in 1657
at Pisa the true structure of the testicle), the generation and
nutrition of both plants and animals, and even the nature of
several diseases.

When we pass in review the various instances of the
firm, sharp, decided way in which Borelli laid hold, with his
physical methods, of a whole series of problems, taken from
nearly all parts of physiology, in dealing with which while we
can now see how often he went wrong, we must also acknow-
ledge how often he was right, how often he brilliantly hit the
mark, two reflections force themselves upon us.

In the first place when we remember that Borelli's book
was published some fifty years only after the appearance of
Harvey's work, and that he appears to have been teaching
publicly much that is contained in it very many years before it
was published, we are impressed with the enormous progress in
physiology during the interval, a progress due in the main to
the development of the new physical mechanical mathematical
philosophy.

In the second place when we consider the effect which a
perusal of Borelli*s book has upon the reader now, we can
easily understand how he was a founder of a great school
which flourished long after him. He was so successful in his
mechanical solutions of physiological problems that many
coming after him readily rushed to the conclusion that all such
problems could be solved by the same methods. And as is
often the case, the less qualified, alike as regards mechanical
as well as physiological knowledge and insight to follow in
Borelli's path were the men of succeeding times, the more
loudly did they often proclaim the might of Borelli's method.
Thus there came in the times after Borelli a school, who
imitating and often mimicking Borelli, proposed to explain
all physiological phenomena by the help of mathematical
formulae and of hypotheses concerning forces and the shapes
and sizes of particles, the iatro-mathematical, or iatro-physical
school whom I shall frequently have occasion to mention in
succeeding lectures.

6—2

LECTURE IV.

MALPIGHI AND THE PHYSIOLOGY OF GLANDS
AND TISSUES.

The rapid development of mechanical and physical science
was not the only event taking place in the beginning of the
seventeenth century which profoundly influenced the progress
of physiology. The introduction of the microscope, though
acting in a different way, proved itself an aid of almost equal
importance to biological studies, though its effects did not
make themselves felt until more than half the century had
run its course.

The anatomists of the sixteenth century, and of the early
part of the seventeenth century, were content like their fore-
fathers to carry on their studies with what we now call the
naked eye, unassisted by any optical instruments. Hence their
statements as to the finer structure of the various organs and
parts of the body were necessarily vague and incomplete.
They could tease certain parts more or less completely into
strands of greater or less thickness and hence could speak of
fibres and of fibrous structure. They recognized skins and
membranes of various thickness. They were able to distinguish
what we call fatty or adipose tissue by means of its gross
features. And they could follow out the blood vessels and later
on the lymphatic vessels until these were lost to view as minute
channels. Beyond this, they were content to speak of that
part of the substance of an organ which could not be split into
fibres, and into which the minute vessels seemed to disappear,
as * parenchyma/ using the word introduced in ancient times by
Erasistratus, but no longer attaching to the word the original

LECT. iv] Malpighi and the Tissues. 85

meaning of something poured out from the veins. By paren-
chyma they simply meant the parts which were not distinctly
made up of fibres and which in most cases at least were porous.
Thus Harvey speaks of the blood which flows along the
pulmonary artery as being discharged into the porous paren-
chyma of the lungs and gathered up thence by the beginnings
of the pulmonary veins. The histology, if we may so use the
word, of these older writers was of a simple kind. Glisson, of
whom I shall have to speak later on in other connections, in the
anatomical introduction to his treatise on the liver, gives, in his
usual formal didactic style, a sketch of the current views as to
the morphological constitution of the animal body.

He divides the body into similar parts and organic parts,
the former being determined by the material of which they are
composed, the latter by the form which they assume. This
division comes obviously very near our ordinary division into
tissues and organs.

The similar parts or tissues may be again divided into the
sanguineous, or those which are richly provided with blood, and
the spermatic which are not, but he observes that the differentia
between these is not an exact one.

The spermatic tissues he divides again into the soft, such as
brain, the hard, such as bone, and the tensile ; the last he again
divides into membranous tissues, such as the pia mater and the
peritoneum, fibrous tissues, such as the tendons and ligaments
as well as the fibres of muscle, of the heart and possibly of the
kidneys, and the tissues which are composed of both fibres and
membranes, such as the true skin, the tissues of the intestines
and others.

The sanguineous tissues are the fatty tissues and the
parenchymatous, the latter being either properly sanguineous,
such as the heart, lungs, kidney and liver, or phlegmatic, such
as the testicle, the pancreas and some other glands. He states
that the fleshy parts of muscles as distinguished from the fibres
of muscle are by some regarded as another variety of the
sanguineous tissues, but in his opinion are really paren-
chymatous.

Though when Glisson wrote this, the new aids had already

86 Mdlpighi and the Physiology [lect.

come into use, and indeed he speaks of the advantages of using
optic tubes and microscopes in examining the pores of the
parenchymatous tissues, he himself had obviously had but little
if any recourse to these aids, and his exposition may be taken
as that of the views held before the microscope was effectively
used.

The invention of the microscope, that is of the compound
microscope (for the simple lens was occasionally used from very
early times), is a matter of some dispute. It has been attributed
to Fontana and also to Galileo, but the general opinion is that
the first instrument was invented, some time before 1610,
possibly in 1590, by the brothers Hans and Zacharias Janssen,
of Middleburgh in Holland; the one made by these is said
to have been 1^ feet in length. Cornelius Drebbel, of Alkraaar
in Holland, is howdver credited with having made at almost the
same time an improved and really effective instrument; and
to him the introduction of this new optical aid is mainly due.

It was not until many years after its invention that the
microscope was seriously applied to anatomical studies. Fran-
cisco Stelluti is said to have been the first thus to use it at
Rome in 1625, a year after the new invention had found its
way to Italy ; but the men who by its use opened up a new
path in anatomy and started new ideas were four, Marcello
Malpighi of Bologna, Anton van Leeuenhoek of Delft, Robert
Hooke of London, and Johannes Swammerdam of Amsterdam.
Of these by far the greatest from a physiological point of view
was Malpighi.

Bom at Crevalcore, close by Bologna, where his parents,
well-to-do people, possessed a small farm, on the 10th of March,
1628, the year of the publication of Harvey's book, Marcello
Malpighi entered in 1645 the University of Bologna as a
student in philosophy. In this he made rapid progress, but in
1649 his studies were interrupted by the death almost at the
same time of his father, his mother, and his father s mother.
Full of affection as a boy, and he was no less so as a man, he
was at first prostrated at the loss. Moreover as the eldest of
a family of eight, three of whom next to him were girls, his
hands were full in the settlement of the patrimony, settlement

iv] of Glands and Tissues. 87

rendered all the more diflBcult by reason of a dispute concerning
boundaries which had arisen between the Malpighi family and
the family of Sbaraglia the possessors of an adjoining property.
This dispute was continued on until the end of Malpighi's
days and in course of time widened from a mere quarrel about
land into a bitter and sustained effort on the part of the
Sbaraglia family to do harm in every possible way to Malpighi's
fame and welfare. Hence though he returned to the University
for a short tinne in the succeeding year, it was not until the
year after, in 1651, that he definitely resumed his studies, and
then with the view of entering upon the profession of medicine.

The Obscurantists, the Galenists were at that time still
powerful in the University; but Bartolommeo Massari, Professor
of Medicine, was full of the new learning. Not content with the
formal duties of his chair, he in 1650 gathered together at his
own house some of the younger professors and older students,
forming them into a club to which later on, the number of
members becoming limited to nine, the number of the Muses,
the name of the Corii^ anatomicus was given. Stimulated by
Harvey 8 new views and by the discovery of the lacteals, the
enthusiastic nine made their meetings the occasion not only
for discussions but also for dissections on dead bodies, and ex-
periments on living animals. Into their number the young
Malpighi was soon admitted, and in what he learnt at their
meetings he laid the foundations of his future work. Accurate
and unwearied in study, bright in mind, quick to grasp each
new thing, but withal mild, retiring and affectionate in dis-
position, he soon gained the. love and esteem of his teacher,
and so rapidly did he profit by what he was taught that in two
years, in 1653, he became Doctor in Medicine and Philosophy.

As doctor he had a right to expect that he would be allowed
to deliver a course of lectures; but not only as the pupil of
Massari but also and perhaps by reason of what he was already
shewing himself to be, he was in disfavour with the Obscurantists
in power, and the right was for a time denied him. Meanwhile
he drew closer the bonds which bound him to his teacher by
marrying, in 1654, Francesca, Massari's sister, who, though she
bore him no children, stood by his side until a few weeks before

88 Mdlpighi and the Physiology [lbct.

his death, a tender, cultivated help-meet. The next year both
were plunged in grief by Massari's sudden death ; but in the
year after that, in 1656, Malpighi, who meanwhile had been
bus}dng himself in medical practice, obtained at last a chair,
and was made a Professor of Medicine.

By that time however his already conspicuous ability
had become known outside Bologna, and in the same year
Ferdinand II., Grand Duke of Tuscany, always on the look-out
to encourage and develope the powers of promising young men,
and endeavouring with princely magnificence to make potent
and famous the University of Pisa, created for him there a new
special chair of Theoretical Medicine, or as we might say, of
the Institutes of Medicine, i.e. of Physiology. Malpighi, feeling
acutely the opposition to himself and to his family in his native
city, accepted the oflFer.

Here at Pisa he laboured for three years, enjoying and
stimulated by the brilliant intellectual activity of the place,
where every eflFort to extend the bounds of natural knowledge
was encouraged by not only the approval but also the material
aid of Ferdinand. He profited much by daily intercourse
with the bright minds which he met there, more especially
with Borelli, who had come to Pisa in the early part of the
same year. The two became close friends, being perhaps
drawn to each other by the contrasts of their characters.
Borelli twenty years older than Malpighi, self-asserting, con-
fident, claiming as his own not only what he had done but at
times what had been done by others, angry if his own merits
were not fully acknowledged, impatient of the praises of others,
bore himself, as we have said, in daily life with a taciturn
coldness if not with a rough fretfulness, which kept many who
admired his talents from looking upon him as a friend. Malpighi,
kindly even to softness, ready to give his aflFections to those
who seemed drawn to him, devoted wholly to those who had
won his love, modest and retiring even to timidity, bold only in
the interests of truth and right, never in his own, lived a life
such as the sweet delicate outlines of his face bespoke, beloved
for the sake of himself, even by those who were not competent
to judge of his talents and his works. Two things the two had

iv] of Glands and Tissues. 89

in common ; each of them possessed a fragile frame buflFeted
by repeated ailments, each was moved t« the depths of his
being by a passion for the new learning. Each was able to
learn from the other. Borelli could teach Malpighi the new
mathematical physical learning of the school of Galileo, of which
there does not seem to have been at this time any adequate
exponent at Bologna, so that Malpighi came to Pisa with
much yet to know. Malpighi on the other hand was able to
lead Borelli into pastures of anatomical inquiry as yet new and
fresh to him, for, so far as can be learnt, Borelli*s mind was not,
until he came to Pisa, turned towards those biological problems
which occupied so much of his subsequent life. The work done
by Borelli on which I dwelt in the last lecture, was begun, and
indeed much of it was at least hewn out in the rough, with
Malpighi at his side. Day by day, after their lectures were over,
they met at Borelli's house or elsewhere, either with other
friends present or without them, dissecting, experimenting and
discussing. They even listened to each other's lectures, for
there is a story that at one of Malpighi*s early lectures, the new
doctrines which he expounded so offended his audience, that
they one after the other withdrew, until at last Borelli was left
as the sole listener. Malpighi was ever ready to insist upon the
great help which he received from Borelli, and if Borelli was
less ready to acknowledge what he had gained from his younger
friend, this, in the judgment of posterity seems to have been at
least not less, perhaps greater, possibly much greater than the
former. Much as Malpighi owed to Borelli, great as was the
guidance which in his early years he had from him, he did not
blindly adopt all Borelli's doctrines, and indeed as we shall see
struck out new lines for himself, being in many respects a wider
thinker and a greater man. This later divergence went far
perhaps to bring about in after years some estrangement between
the two ; but during their common stay at Pisa, and for some
time afterwards, their friendship, though tried from time to
time by Borelli's behaviour, remained stedfast; whenever a new
discovery or a new idea came to Malpighi his first desire was to
learn what Borelli had to say about it.

Three years he thus spent at Pisa, teaching and learning,

90 Malpighi and the Physiology [lbct.

busying himself among other things with experiments on the
blood more or less chemical, the results of which he recorded
after the fashion of the time in a Dialogue between a Galenist
and a surgeon of the new school. This however he did not
publish, and the manuscript was accidentally burnt years after
when his house took fire.

Meanwhile the domestic diflSculties touching the paternal
estates at home increased rather than diminished; and probably
in part in order to be on the spot but also for the reason stated
by himself that the humid climate of Pisa, trying to many at
the present day, was injuring his health, he asked permission
of Ferdinand to resign his chair and returned to his native
city.

Here he resumed oflSce as a Professor of Medicine, and, in
spite of domestic troubles and anxieties, pursued his researches
to such good effect that he was able in the next year, 1660, to
announce privately to Borelli his discovery of the structure of
the lung, an account of which was published in the year
following. But his native city did not keep him long. In
1662, the chief or first chair of Medicine in the University of
Messina, then active, flourishing and ambitious, had become
vacant, through the death of P. Castello, and the senate, led to
do so by the urgent advice of Borelli, who as we said in the
last lecture had been professor there, offered, in April, the chair
to Malpighi, accompanying the offer with the promise of a
handsome salary, as well as an adequate sum for the expenses
of the journey. Malpighi for a while hesitated, distrusting
his mental as well as his physical powers, but persuaded by
Borelli, and influenced perhaps by dislike of the intrigues
against him and his family going on in Bologna, finally ac-
cepted and after a brief stay at Naples on the w^ay out entered
upon his duties in the autumn of the same year.

Here for some four years, years fertile as we shall see in ideas,
he remained, unwearied in labours of research, content with
his position and with his work. Here he began a number of
inquiries, some of which brought forth results ready almost
at once to be made known, but others of which needed for
their completion the toil of many years yet to come. Living

IV J of Glands and Tissues. 91

close by the sea-shore he had ample opportunities for studjdng
the anatomy of fishes and other creatures of the sea ; and the
simpler structures which he found in these opened up in his
mind views as to the real nature of the like but more complex
structures of man and the higher animals. It is perhaps not
too much to say that during these four years there came to him
many of the ideas to develope which was the work of his life-
time. His quiet undisturbed life in Messina was the germinal
period of his career.

But Sicily was not his home, and was not to be his home.
When, in 1666, the term of his appointment for four years had
come to an end, the Senate of Messina pressed him, in so
flattering a way, to continue in the chair that he felt unable to
refuse ; but he asked and obtained leave to pay a flying visit to
his native city. This he wished to do for one reason among others
that he might give personal attention to the still troublous
afljEkirs of the family. He set out in the spring, staying on his
journey for a few days at Rome, where he met and made friends
with Stensen. The warm welcome with which he was received
at Bologna was a token of the fame which his researches were
already gaining for him. So great indeed had that fame become
that his enemies could not withstand it, and his friends found
themselves in a position to offer him the Chair of Medicine in
his native city. This Malpighi accepted, and the Senate of
Messina though much against their will set him free from the
promise which he had made to them. He never returned to
Sicily, but definitely took up once more a place in his old
University. Here for a quarter of a century he remained,
labouring not only in season but also out of season, for the
feebleness of his body brought to him again and again times
in which he ought to have folded his hands, but in which his
active mind kept him still at work. Here he gave his lectures,
here he went about healing the sick, and here all the time the
best energies of his mind were being given to the task of
penetrating the secrets of nature hidden in living bodies. He
published the results of the inquiries which he had finished
at Messina, he completed those which he had only begun there,
and he carried on others wholly new. During the winter the

92 Malpighi and the Physiology [lect.

duties of his chair kept him closely confined to the city ; but
in the summer, when his lectures were over, it was his custom
to retire to some quiet spot in the country near. Here, free
from the interruptions incidental to a town life, he could give
unbroken attention to his inquiries; the calm repose and the
pure air of the fields gave renewed vigour to his feeble frame ;
and, in the loving company of his devoted wife, he spent golden
days, observing, thinking and writing.

While he was yet at Messina the fame of his discoveries
had reached the distant shores of England, and on his return to
Bologna he received in 1667, forwarded to him from Messina, a
letter from Oldenburg, the secretary to the newly established
and almost feverishly active Royal Society of London, inviting
him to a philosophic correspondence. That letter was the
beginning of a long and close intercourse between the Italian
philosopher and the English learned Society, one fruit of which
was that the Royal Society had the honour of publishing and
of bearing the expense of publication of the greater part of
Malpighi's works, in fact with some slight exceptions of all
the works which he produced after his return to Bologna.

Were I to attempt to do full justice to the memory of
Malpighi I should have to go far beyond the limits of the
subject of these lectures. He was the founder of, he opened
up the path of inquiry in more than one branch of biological
knowledge. He with the Englishman Nehemiah Grew laid the
first sure foundations of vegetable morphology. While at
Messina, walking one day in the garden of his friend and
patron the Visconte Ruffo, snapping the branch of a chestnut
tree which overhung and obstructed the path along which the
two friends were walking his attention was arrested by the
vascular bundles, projecting and hanging down from the broken
end of the branch. This led him to study, and afterwards to
write an immortal book on the Anatomy of Plants. The first
sketch of this he sent to the Royal Society of London, which
subsequently published the full work, and the day, December 7,
1671, on which it was presented and read before the Society
happened to be the day on which Grew presented to the
Society his printed book * The Anatomy of Vegetables begun,'

iv] of Glands and Tissues. 93

the order to piint which had been given at a meeting of the
Council of the Society in the previous May. The two inquirers
struck upon the same ore, at the same time ; and to both credit
is due. But everyone who has read the two works by the two
men must acknowledge that while that of the Englishman is
a sound piece of honest, arduous labour, that of the Italian, no
less sound, though perhaps less abounding in valuable detail,
shmes, more than does the other, with the light of genius, and
is richer than the other in philosophic insight.

Malpighi may also be regarded as, almost in the same
degree, the founder of that great and important branch of bio-
logical science which we call embryology. LoDg ago Aristotle
had seen and studied the chick forming in the egg. Mure
recently as we have said Fabricius had examined and de-
scribed at some length the same mysterious events. Harvey
in his later years had given his mind to the problem of
the generation of animals. But none of these had gone very
far. The first adequate description of the long series of changes
by which, as they melt the one into the other, like dissolving
views, the little white opaque spot in the egg is transformed
into the feathered, living active bird, was given by Malpighi.
And where he left it, so for the most part the matter remained
until even the present century. For this reason we may speak
of him as the founder of embryology.

He was also a zoologist, at least a comparative anatomist.
Surrounded as he was in Italy, and even more so in Sicily
by cultivators of the silkworm, his correspondent Oldenburg,
the secretary of the Royal Society, had in his letter invited
him "to make the Society acquainted with any observations
"made in Italy which he might think worthy of recounting,
"and in particular observations on the silkworm and its
" economy." Malpighi accordingly devoted himself to an ex-
haustive study of the silkworm in its various phases, examining
not only its outward form but also the internal arrangement
and the minute structure of all its viscera, leaving his name
as Malpighian tubules on certain of them, and tracing out
the whole history of the creature from the egg to the perfect
insect. The results at which he arrived he embodied in a

94 Malpighi and the Physiology [lect.

treatise presented in the form of a letter to the Royal Society,
the first of his books published by that body.

This was his chief work in comparative anatomy, a model
work of supreme excellence, but he also made many other
valuable observations on various animals, vertebrate and in-
vertebrate.

Malpighi was no mere professor, his time was not spent
wholly in the laboratory and lecture room. He was actively
engaged in healing the sick, he was as familiar with the
phenomena of disease as with the phenomena of the healthy
living being. He brought to bear on the former the same
clear intellect which he turned towards the latter, seeking to
find out the causes of the events which he witnessed. He
was as busy in the post-mortem room as in the dissecting
theatre, and his writings on the characters and causes of disease
justify us in claiming for him the merit of haviug laid the
foundations of scientific pathology.

But it is not of Malpighi as botanist, as embryologist, as
naturalist, as pathologist, or as biologist, for from his varied
studies he stands out as the man who first of all others laid
firm hold of the fundamental principle of the essential identity
of vegetable and animal life, that I have here to speak. He was
all these, but he was also the first who calling into his aid the
newly invented microscope, opened up the way for a true grasp
of the minute structure of the tissues and organs of the animal
body, and in so doing opened up also a new branch of physiology.
He was the first histologist, and with the new histology came
new ideas of the functions of many important parts of the body.

To Vesalius, to Fabricius and to Harvey, who looked upon
the animal body as composed of a number of organs deftly
joined together, the problems of physiology presented themselves
as a number of special problems of a mechanical nature, capable
of being solved by mechanical methods, except in so far as, to
use Vesalius' words, the qualities of the proper substance of
each organ supplied the determining factor of its functions.
The microscope revealed to Malpighi features of structure
transcending mere mechanical notions. He saw that the tissues
in their minuter structure were governed by laws of their own,

iv] of Glands and Tissues. 95

by laws different from those which determined the uses of
machines ; and thus there came to him the new conception of
an animal morphology. And his views broadened as, while
still regarding the study of man's structure as his first duty, he
pushed his researches into the structure of many animals,
vertebrate and invertebrate, and also of plants. All these
studies more and more revealed to him general plans of struc-
ture and common laws of growth. As Harvey had been led to~l
new views by studying the uses of animal organs viewed as
machines, as Borelli had been led to other new views by
regarding the phenomena of the animal body as subject to
ordinary physical laws, so Malpighi was led to still other new
views by this new thought that the material of the living body
was subject to, and so its functions determined by, laws of
structure proper to itself, laws which we now call morphological.

The first work which he published was that * On the Lungs'
{De pulmonibus observationes anatomicae) in 1661, in the form
of two letters to his friend and master Borelli, describing the
results of an inquiry which he carried out at Bologna im-
mediately after his return from Pisa. Up to that time little
or nothing was known of the real structure of the lung. It
was spoken of as fleshy, and its substance, which Fabricius had
compared to tow, was held to be a porous parenchyma, in which
the minuter divisions of the blood vessels on the one hand and
of the windpipe on the other were lost. It was into the spaces
of this porous fleshy parenchyma, as we have said, that the
blood of the pulmonary artery was supposed to be poured,
thence to be gathered up by the beginnings of the pulmonary
veins.

In these brief epistles Malpighi announced two discoveries
of ftindamental importance. In the first letter he described
the vesicular nature of the lung and shewed how the divisions
of the windpipe ended in the dilated air vesicles. He thus
for the first, time supplied an anatomical basis for the true
conception of the respiratory process.

In the same epistle he describes the network of blood
vessels, of arteries and veins (it may be worthy of note that
Malpighi always speaks of the pulmonary artery and pulmonary

96 Malpighi and the Physiology [lect.

veins, the old term of the artery-like vein, and the vein-like
artery having by this time become obsolete) winding over the
air vesicles, but he could not as yet (he was so far working
chiefly on the lungs of dogs) satisfy himself on the point
whether or no the blood escaped from the miuute arteries into
empty spaces whence it found' its way into the minute veins.
A little later he turned his attention to the simpler luDg of the
frog, and in this he had the happiness, calling into his aid the
microscope, to see that minute but definite channels, the
channels which we now call capillaries, joined the endings of
the minute arteries to the beginnings of the minute veins.

In his second epistle to Borelli, after describing, under the
heading * I see with my own eyes a certain great thing/ the
appearances presented by the lung of the living frog extruded
after the laying open of the body, which organ he says *'is
" nothing else than a sort of membranous bladder which at fii*st
"sight seems to be sprinkled over with very little spots
" disposed in an orderly fashion like the skin of the dog-fish,
" commonly called Sagrino," he thus continues :

** Something still more wonderful than the above appearances
"which relate to mere structure and build is disclosed by
" microscopic observation. For, while the heart is still beating,
"two movements contrary in direction though accomplished
" with difficulty are observed in the vessels so that the circu-
" lation of the blood is clearly laid bare ; and indeed the same
" may be even more happily recognized in the mesentery and in
" other larger veins contained in the abdomen. And thus by
"this impulse the blood is showered down in minute streams
"through the arteries, after the fashion of a flood, into the
" several cells, one or other conspicuous branch passing right
" through or leaving oflF there, and the blood, thus repeatedly
" divided, loses its red colour, and, carried round in a sinuous
" manner, is poured out on all sides until it approaches the walls,
" and the angles and the absorbing branches of the veins.

"The power of the eye could not be carried further in
"the opened living animal; hence I might have believed
"that the blood itself escaped into an empty space and was
"gathered up again by a gaping vessel and by the structure

iv] of Glands and Tissues. 97

"of the walls. Bat an objection to this view was afforded
** by the movement of the blood being tortuous and scattered
"in different directions and by its being united again in a
"determinate part. My doubt was changed into certainty by
" the dried lung of the frog which to a very marked extent had
" preserved the redness of the blood in very minute tracts (which
" were afterwards found to be vessels) where by the help of our
" more perfect glass there met the eye no longer scattered points
" resembling the skin which is called Sagrino, but vessels joined
" together in a ring-like fashion. And such is the wandering
" about of these vessels, as they proceed on this side from the
" vein and on the other side from the artery that the vessels na
"longer maintain a straight direction, but there appears a
"network made up of the continuations of the two vessels.
" This network not only occupies the whole area but extends
" to the walls, and is attached to the outgoing vessel, as I could
"more abundantly and yet with greater diflBculty see in the
" oblong lung of the tortoise, which is equally membranous ^nd
" transparent. Hence it was clear to the senses that the blood ^
" flowed away along tortuous vessels and was not poured into \
" spaces, but was always contained within tubules, and that its
" dispersion is due to the multiple winding of the vessels.
" Nor is it a new thing in Nature to join to each other the
"terminal mouths of vessels, since the same obtains in the
"intestines and other parts; and, indeed, what seems more
"wonderful, she joins together by a conspicuous anastomosis
" the upper and lower terminations of veins as the most learned
" Falloppius has very well observed.

"In order, however, that you may more easily grasp what
" I have just stated, and follow it with your own eyes, ligature
" with a thread at the spot where it joins the heart, the pro-
" truded and turgid lung of a frog whose body has been laid
"open, doing this while a copious supply of blood is flowing
** through the whole of it.

" This even when dried will preserve its vessels turgid with
" blood. And this you will see exceedingly well if you examine
** it with a microscope of a single lens against the horizontal
*' sun. Or you may adopt another method of seeing these things.

p. L. 7

98 Malpighi and the Physiology [lect.

" You will place on a transparent plate the lung, illuminated from
" below by the light of a lamp conducted through a tube and
" you will bring to bear upon it a microscope of two lenses. In
" this way the vessels distributed in a ring-like fashion will be
" disclosed to you. By the same arrangement of the instrument
" and the light you will observe the movement of the blood in
" the vessels lying in the field of view. And you will yourself
" be able, with different degrees of light which escape description
" by the pen, to devise other things. Concerning the movement
"of the blood, however, one thing presents itself as worthy
"of your speculation. The auricle and heart being ligatured
" and so all movement and impulse which might be conveyed from
"the heart to vessels still connected with it being removed,
"the blood still flows towards the heart along the veins and
"distends these by its movement and copious supply; and
"this lasts for several hours. At the end however, especially
"if it be exposed to the sun's rays, it is not the subject of
" the same continued movement but as it were of alternating
** impulses; the blood, moving to and fro, progresses and then
" recedes along the same way. And this takes place also even
" when the heart and auricle have been removed from the body.

*' Turning therefore to the former problems demanding
" solution, it may, by analogy, and from the simplicity which
" Nature uses in all her works, be concluded from these results
" that that network which I once thought to be nervous in nature
" is really a vessel attached to the vesicles and sinuses carrying
" thither the mass of the blood or carrying the same away, and
" that although in the lungs of the more perfect animals a vessel
" seems sometimes to leave off and to gape in the middle of the
" network of rings, yet it is probable that, as in the cells of the
" frog and the tortoise, the vessel in question is prolonged further
" into very small vessels after the form of a network, although
" these on account of their exquisite fineness escape our senses."

This was the first observation of the capillaries. A few
years later, in 1668, that patient and accurate Dutch observer
Anton van Leeuwenhoek observed them in fishes and in
anophibia, and gave a fuller description of them. With the clue
thus given their presence was shewn or taken for granted in all

iv] of Glands and Tissues. 99

other structures, and it soon became acknowledged that the
circulation was a more complete mechanism even than Harvey
had supposed, that the blood flowed in wholly closed channels
from the heart through arteiies, capillaries, and veins back to
the heart again. A sound view of the processes of nutrition
thus became possible, and it was Malpighi who first found the
missing link in the chain of Harvey s discovery.

In a little tract on the omentum, fat, and adipose ducts (De
oniento, pinguedine, et adiposis ductihus) published four years
later, in 1665, in company with three other tracts of which I
am about to speak, Malpighi records an observation which shews
that he had hit upon another discovery touching the blood ;
but he failed to lay hold of the meaning of what he saw. Up
to this time the redness of red blood had been supposed to be
diffused over the whole fluid. Malpighi in describing the fat-cells,
of which he found the fat of the omentum to be composed, states
that, using the microscope, he fancied he saw small flat red cells
in the mesenteric blood-vessels of the hedgehog (his anatomical
histological studies were carried out on almost all manner of
animals). This is what he says:

"And I myself in the omentum of the hedgehog in a
" blood vessel which ran from one collection of fat to another
"opposite to it, saw globules of fat, of a definite outline,
"reddish in colour. They presented a likeness to a chaplet
" of red coral.''

He mistook however the nature of what he saw. What
evidently were blood corpuscles he thought to be fat cells
passing from the fatty tissue into the current of the blood.

Meanwhile in thus seeing red blood corpuscles he had been
anticipated by the great Dutch observer of minute structures,
Johannes Swammerdam of Amsterdam. That great work of
patient conscientious industry, Bihlia Naturce, though not
published until 1738, and then by Boerhaave, long after the
author's death in 1680, contains the record of an observation
made so early as 1658, seven years before the appearance
of Malpighi's tract. Speaking of the blood of the frog he
says:

" In the blood I perceived the serum in which floated an

7—2

100 Malpighi and the Physiology [lect.

** immense number of rounded particles, possessing the shape of
"as it were a flat oval but nevertheless wholly regular. These
"particles seemed however to contain within themselves the
"humour of other particles. When they were looked at sideways
" they resembled transparent rods as it were and many other
"figures, according, no doubt, to the different ways in which
" they were rolled about in the serum of the blood. I remarked
" besides that the colour of the objects was the paler the more
" highly they were magnified by means of the microscope."

After this we owe the first real accurate description of the
red corpuscles to Leeuwenhoek, who in 1674 in the Philosophical
Transactions gave an account of the red blood corpuscles in man,
and in various papers carefully described the blood corpuscles of
different animals, shewing that while circular in mammals they
are oval in birds, frogs and fishes, and proving that in all cases
the redness of blood is due to these red bodies.

The discovery of the capillaries and the first observation of
red blood corpuscles were achievements of no mean value ; but
still more important perhaps than these were Malpighi's
labours, many and varied, on the structure of glands and
glandular organs.

Before I go on to speak of these however I must say a
few words concerning two little tracts which he published in
1665 during the last year of his stay at Messina, one on the
tongue {De lingua exercitatio epistolica), addressed to Borelli,
the other on the external organ of sense (De externo tactus
organo exercitatio epistolica), addressed to his Sicilian patron
Ruffo.

Fabricius had made known the distinction between dermis
and epidermis. The papillae of the tongue, being qbvious
structures, had long of course been known; but the general
opinion was that they were organs secreting fluid and so
helping to keep the mouth moist; and the papillae of the
skin were wholly unknown.

Malpighi, beginning to work on the tongue, but extending
his researches to the skin, discovered that lower layer of the
epidermis, the rete miLCosum, which we more frequently now
call after him the Malpighiam layer. The fact that the surface

iv] of Glands and Tissues, 101

of the tongue, when well dried, remained dry when kept ex-
tended out of the mouth, shewed him that the papillae could
not be structures whose purpose was to secrete fluid. He
traced the distribution of the nerves to them and concluded
that they were organs of taste. Having arrived at this view,
the thought occurred to him that the sense of touch might be
served by similar organs in the skin whose general structure
was so like that of the tongue. Knowing what to look for, he
soon found that for which he was seeking. He was soon able
to demonstrate the existence of papillae in the skin ; and the
fact that they were most abundant in those regions in which
the sense of touch was most acute convinced him that he had
in them discovered the organs of touch.

At the same time he published also in a letter to his old
fellow student at Bologna, Fracassato, a tract on the anatomy
of the brain {De cerebro exercitatio epistolica). An important
work on this subject had in 1664 been published by the
Englishman Willis, whose name remains to us in the terra
* circle of Willis.' That book, of which as well as of other
labours of Willis I hope to speak in the proper place, contains
much that is valuable, but it was as yet unknown to Malpighi,
whose results were arrived at independently.

In this tract he shews with the help of the microscope that
the white matter consists of round but flattened little fibres
arranged in bundles whose course is diflScult to follow, but
which in any case form tracts connecting the surface of the
brain with various regions of the spinal cord. He further
shews that the grey matter is not confined to the surface of the
brain where it is called cortex, but exists in scattered masses
in the interior, disposed around the ventricles, and along the
spinal cord. The nature of this grey matter he is in this
tract unwilling to define exactly, but when he returned to the
subject a little later he concluded that it was of a glandular
nature.

In this he was misled by his success in investigating
the glandular organs in general, the results of his inquiries
into which were published in 1666, the year he left Messina,
under the title of De viscerum structura exercitatio anatomica.

102 Malpighi and the Physiology [lect.

To these researches we must now turn ; and we may here fitly
consider together with Malpighi*s labours those of other men
studying the same subject.

For this purpose it will be well to go back a little and pass
in brief review what were the views held in the days before
Harvey concerning the functions of the structures known as
glands. Under the term gland however many of the older
writers included also many other organs, such as the brain and
the tongue, in fact almost all the viscera except the heart and
alimentary canal ; for their point of view was that of gross
anatomy, not like ours that of physiology.

Of these glands attention was directed chiefly to three, the
liver, the spleen, and the kidneys.

The functions of the kidney seemed in some respects fairly
simple. Amply supplied with both veins and arteries, the
substance of the kidney, strained off as Vesalius says from the
blood not only of the veins, but also of the arteries, some but
not all of the serosity ; and this gathered in the pelvis of the
kidney as urine was conducted by the ureters to the bladder.
The great difficulty was to understand how the substance of the
kidney, dense and firm, most like the substance of the heart,
says Vesalius, though destitute of fibres of its own, these being
supplied only by its own arteries, veins and nerves, could effect
this straining.

The functions of the liver too seemed to the men of those
times to be fairly well understood by them ; the view which
they took was somewhat as follows. The vena portae carried
to the liver nutritive material gathered up from the stomach
and intestines, and by the excessive branching within the
liver brought that material within the grasp of the soft
parenchymatous hepatic substance. By help of this substance
a concoction was effected, a sort of fermentation was carried
on. In some such way as the crude juice of the grape is
fermented into wine, with the separation on one hand of the
heavier faex which settles to the bottom, and of the lighter foam
which rises to the top, so the crude gross blood of the vena
portae was purified by the hepatic substance into the purer
blood which made its way by the vena cava to the heart, through

iv] of Glands and Tissues. 103

the separation of two impurities. Of these the one, the lighter
one, corresponding to the foam or yeast of fennenting must,
escaped as yellow bile into the minute beginnings of the biliary
duct, and was thence carried to the gall-bladder, from which it
from time to time escaped into the duodenum. The other, the
heavier muddy impurity, passed back as black bile, according
to common belief Vesalius says, meaning thereby that he did
not believe it, to the spleen, being carried thither by the
veins.

About the spleen itself there was more divergence of
opinion. Admitting that the black bile carried to it from
the liver was by the substance of the spleen acted upon and
altered in some way, authorities were not agreed as to what
followed. Most were of opinion that black bile acted upon by
the spleen was poured into the stomach, and so passing through
the intestine was discharged with the faeces, having in the
stomach, if not along the intestine, served some useful purpose.
But while some maintained that there was a definite canal,
leading from the spleen to the stomach, and indeed to the
cardiac end of the stomach, along which this modified black
bile passed, others supposed it to be carried by veins. Vesalius
is very sarcastic over both one and the other of these as well as
over other views of this matter, and scoflfs at those who are
anatomists by imagination and not by dissection. He obviously
did not believe in any passage of material at all from the spleen
to the stomach, whether by a special duct or by the veins. But
the view was in onfe form or other very generally adopted ; it
served as the theoretic basis of medical practice, and is still
preserved in the popular phrase of suffering from the spleen.

Other glandular bodies such as the pancreas, the salivary,
glands, the thymus and the thyroid, were known, as well as the
lymphatic glands scattered over different parts of the body;
little attention however was paid to these. Neither salivary
glands nor pancreas were known to possess ducts ; and all these
vaiied bodies were regarded, if noticed at all, from the same
point of view.

It will be remembered that before the establishment of
Harvey's views blood was supposed to be carried by the veins

104 Malpighi and the Physiology [lect.

to organs as well as from organs; and the ideas just sketched
were in large measure based on the assumption of this double
venous flow and ebb, to and fro. Hence, when the proof
came that in each organ blood flowed to the organ through
the arteries alone, through the organ from the arteries to the
veins, and away from the organs along the veins always in one
direction all these old views demanded reconsideration.

We shall have to consider some of the glands again from
the point of view of the uses of their juices, when we come to
discuss the development of the more chemical side of physiology.
Meanwhile we may treat them from the point of view of the
mechanism of secretion aud of the relation of this to the vascular
system ; this was the point of view of Malpighi, who entered
very slightly, indeed hardly at all, in the discussion of chemical
problems.

The first stop was taken by John George Wirsung, who
though a Bavarian by birth held in the middle of the seven-
teenth century the once so famous chair of Anatomy at Padua.
In a letter to Riolan dated 1643, he described the duct of the
pancreas which he had discovered the year before. He speaks
of its entrance into the duodenum close to the mouth of the
biliary duct, and of its i*amifications in the body of the pancreas.
He says that he found it easy to pass a style through from the
body of the gland into the duodenum, but difficult to pass the
style from the duodenum into the duct, that the duct is present
in man at all ages, that he found it in all the animals which he
had examined, and that it could not be either an artery or a
vein, since it never contained blood, but on the contrary was
often filled with a nearly colourless fluid which like bile stained
a silver style.

Wirsung's pupil John Maurice Hofmann claimed the dis-
covery as his own, as one made by himself and laid hold of
by his master; but there is no satisfactory evidence of this.
Wirsung met some years afterwards with a tragic death, being
shot as he was entering his house at night ; the legend states
that a quarrel about the discovery of the duct was the cause
of the murder, but it seems to have been the result of some
private grudge.

iv] of Glanids and Tissues. 105

Wirsung never followed up his discovery of the pancreatic
by any study of the function of glands; and the new fact
remained, so far as he was concerned, barren.

The next step was taken by the Englishman Thomas
Wharton, who, born in 1614, seems to have carried out his
medical studies exclusively in London, where he subsequently
practised as a physician, being a great friend and ally of Glisson.
In 1656 he published under the title of Adenographia, an
exhaustive treatise on glands, the outcome of the anatomical
lectures which he had given at the College of Physicians in
1652. In this he describes the anatomy, i.e. the external form
and naked eye structure (for he does not seem to have used the
microscope), and especially the arrangement of nerves, blood
veasels and lymphatics, of all those organs in the body which he
called glands, including in that term the brain and tongue. In
the course of his description he gives an account of the discovery
which he had made of the duct of the submaxillary gland, the
duct which has since borne his name. He insists that by this duct
real saliva, not mere phlegm or mucus, is discharged into the
mouth. He also developes a theory of the use of glands, both
of those having a duct and of those having none, which is worth
noticing as illustrating some of the views of the period. While
not denying that the blood brought to the gland by the arteries
supplied the gland with material, and, in the case of a gland
with a duct, furnished a part at least of the juice, he attached
much greater importance to the nerves, and to the sticcus
nerveus, which they canied ; he like Borelli and others adopts
this new term for the old animal spirits. He points out that
most glands are richly provided with nerves, and argues that
these nerves play one or other or both of two parts. They
either give up something by the removal of which the succus
nervous is purified, the too great humidity of the nerves being
thus lessened, the matter so transferred from the nerves to the
gland leaving the gland by its duct, or in the absence of
a duct, by the veins or lymphatics; or they take something
from the gland by which means the succus nerveus is fortified.
It is obvious that Wharton was far from grasping the
true meaning of his remarkable discovery.

106 Malpighi and the Physiology [lect.

The next step was taken by Nicolas Stensen, in Latin,
Nicolaus Steno, the Dane of whom I have abeady spoken, and
who in J 661 discovered and in the following year described the
duct of the parotid gland, since called by his name.

Before speaking of this part of Stensen's work, I should like
to say a few words about the life of this remarkable man.

Born at Copenhagen on January 10, 1638, his father being
a court jeweller, zealous beyond measure in Lutheran doctrines,
he studied medical subjects first in his native city under
Bartholin, who assisted largely in the development of the
knowledge of the lymphatics then taking place, subsequently
at Leyden under Sylvius, of whom I shall later on have to
speak, and later on under Blasius at Amsterdam. It was
while at work dissecting in the house of the latter that he
made his discovery of the duct.

His studies however had not been narrowly medical; as
shewn by his work on muscle of which we spoke, he had laid
a firm hold on the new mathematical and physical learning.

After publishing in 1662, while as yet a young man of
twenty-four years, his Observationes AnatomiccB relating his
discovery of the parotid duct, he travelled much in Germany,
France, and other countries, mixing with learned men, learning
not a little and also teaching not a little wherever he went. It
is said that at Paris he attracted the attention of the great
Bossuet, who desired to convert him to the Catholic religion,
but Stensen told him that he was far too busily occupied with
science to be able to attend to such matters. At one of his
visits to Paris he was invited to deliver at a meeting of learned
men held in the house of Th^venot, a discourse on the Anatomy
of the Brain. In this discourse, published in 1669, which we
have already quoted, he criticizes in a fearless and severe
manner, from the point of view of the exact anatomist and
physiologist, the fanciful and popular views put forth by
Descartes.

After a while, in 1666, he came to Italy, staying some time
in Padua, and then going on to Pisa. Here he attracted so
much attention that Ferdinand II. invited him to Florence to
be Court Physician, a post in which Cosimo III. on his sue-

iv] of Glands and Tissues. 107

cession confirmed him, entrusting him at the same time with
the education of his children.

While thus engaged, still working at physiology, he turned
his versatile mind to other problems as well, to those of
comparative anatomy, and especially to those of the infant,
indeed hardly as yet bom science of geology. His work Dp.
solido intra solidtcm is thought by geologists to be a brilliant
eflFort towards the beginning of their science.

In 1672 he returned for a while to his native city of
Copenhagen, but within two years he was back again at
Florence; and then there came to him, while as yet a young
man of some thirty-six summers, a sudden and profound change
in his life.

In his early days he had heard much, too much perhaps, of
the doctrines of Luther. Probably he had been repelled by
the austere devotion which ruled the paternal roof. And, as
his answer to Bossuet shews, his university life and studies, his
intercourse with the active intellects of many lands, and his
passion for inquiry into natural knowledge had freed him from
passive obedience to dogma. He doubtless, as did many others
of his time, looked upon himself as one of the enlightened, as
one raised above the barren theological questions which were
moving the minds of lesser men.

One day however visiting at Florence the pharmacy
attached to Santa Maria Novello (the same pharmacy at which
to-day you may buy orris root and other preparations), in order
to purchase some drug, the holy brother who sold him the
medicine for the body dropped some words about the remedies
for the soul. The stray arrow entered between the joints of
the harness. New thoughts were stirred up in the mind of
the man of science and of the world ; and within a year, to
the astonishment of his friends, and to the dismay of all
friends of the new learning, he forsook all his old studies,
gave up all inquiry into the works of nature, and by taking
orders solemnly devoted himself henceforward to the works of
God and religion.

A convert of such powers and of such a fame could not but
be warmly received by the Church ; and in 1677, receiving the

108 Malpighi and the Physiology [lect.

titular honour of Bishop of Titiopolis in Greece, he was sent as
Vicar Apostolic to the northern countries of Europe in the
hope that he might win back to the true faith many of the
erring ones in the land in which he had been born and bred.

Led apparently by the thought that he might turn the old
weapons which he had wielded so well to the use of his new
purposes, he began once more to teach anatomy in his native
city of Copenhagen, the strange position of a Catholic Bishop
professing a mundane subject in a heretic university being
accepted by the authorities, and approved by the Church. But
the position was false as well as strange ; the changed voice no
longer as of old spoke with authority and power ; the zeal for
knowledge which had in old days charmed men as they
listened to him, no longer made itself felt ; and zeal for good,
however fervent, could not take its place. Stensen soon saw
that it was false ; he gave up wholly all such attempts to work
his old life into his new calling. Resigning his chair he hence-
forward devoted himself to the more usual duties of a priest.
For nine years he lived in Germany, first at Hanover and then
at Schwerin, a life of severe self-denial, labouring constantly
for the welfare of the poor, with no thought but that of
winning souls for the Church. The privations which he laid
upon himself, and the toils which he underwent for others,
were too much for the body, which had once filled so much of
his thoughts, and which he now held as a thing of nought.
He wore himself to death ; and in 1686 at the relatively early
age of forty-eight passed away. The brilliant achievements of
his early days and the sanctity of his later life made his name
in different ways precious at Florence ; and at the command of
the Duke of Tuscany the emaciated corpse of one who had
been at once an apostle of science and a martyr to the calls of
religion was brought back to Florence and buried with public
honours in the city fitted perhaps above all others to receive it,
as being, like the dead one, at once famous for learning and
zealous for the Church.

Stensen gives a graphic description of his discovery of the
parotid duct. He relates how, while he was residing with and
studying under Blasius, one morning, when he was engaged in

iv] of Glands and Tissues. 109

dissecting the head of a sheep and examining the parotid gland,
the style which he was using, inserted by chance it would seem
into an opening in the duct, slipped easily down and struck with
a sharp clink against the teeth ; he recognized that he had dis-
covered the duct of the gland. Wharton as we have seen had
just before discovered the submaxillary duct ; but the two men
made very different uses of their two discoveries. Wharton
blundered, led away by current ideas of the nerves and their
animal spirits. Stensen, who had learnt from his master Sylvius
of Leyden the distinction between conglomerate glands, such as
the salivary glands and the pancreas, and conglobate glands,
such as the lymphatics, laid hold of the idea that the former
were secretory glands and hence must all have ducts. He soon
found the duct of the sublingual gland, as well also as those of
the small buccal glands, and cleared up the problem of the
secretion of tears by the lachrymal gland, concerning which
in spite of the lead given by older anatomists there was as
yet much confusion. Further so far as he was able, seeing that
he appears to have used the simple lens chiefly and the micro-
scope very little if at all, and that he had as yet no knowledge
of the capillaries, he formed a conception of the process of
secretion which went very near to the truth and served as
a useful basis for further inquiry.

He recognized that the material for the production of saliva
or of any other secretion of a secreting gland is brought by the
blood of the arteries and is given up in the substance of the
gland to the beginnings of the duct, as the blood is passing
from the arteries to the veins by which it leaves the gland. He
seems to have wanted only a knowledge of the minute micro-
scopic structure of the gland, and of the relation of the
capillaries to the secreting vesicles ; had he possessed these he
might have given an account of the process such as would be
accepted even at the present day. As it is, his views stand in
bright contrast to those of Wharton. Nerves, he says, serve
only for movement or for sensation, and the nerves of a gland
are of use for these purposes only. He speculates how the
action of the nerves by inducing movement can affect the flow
of saliva, and throws out the idea that it may be by bringing

110 Malpighi and the Physiology [lect.

about constriction of the veins, since this by opposing the flow
of blood would throw more material into the beginnings of the
duct.

He is very clear as to the essential difference in nature
between the conglomerate (secreting) glands provided with
ducts and the conglobate (lymphatic) ductless glands, and
points out that lymph flows only from the former, whereas
it flows to and through the latter on its way to the venous
system.

In yet another organ another discovery, an important aid to
the doctrine of secretion, was made about this time.

In the year 1662 a pupil of Borelli s, one Laurentio Bellini,
a Florentine of good family, whether or no related to the great
Venetian painters I cannot tell, published a little tract De
structura renum. He was then a mere youth of 19 years.
The Duke of Tuscany had sent to Borelli a deer to be used
for anatomical purposes, and Bellini, under Borelli's guidance,
carefully examined the kidneys. He then saw what no one
had seen before, that the substance of the kidney was composed
of minute tubules, urinary canaliculi, radiating from the pelvis
towards the surface. Eustachius had seen something of these,
but he described them as 'fuscous sulci'; it was Bellini who
really grasped their nature, and these straight tubuli uriniferi
(for he did not distinguish between the twisted and the straight
tubules) have since been known by his name. He described
the tubules as opening into the pelvis of the kidney, and guided
by the mind of his master Borelli expounded a physical theory
of the secretion of urine. The minute arteries, he says,
discharge their contents into spaces in the parenchyma of the
kidney, whence the aqueous serosity of the blood passes into
• the beginnings of the urinary canaliculi, while the rest of the
blood finds its way out by the veins. The selection of the one
path and of the other is determined by the size and configura-
tion of the particles ; those of the aqueous serosity fit into the
canals of the canaliculi, those of the rest of the blood do not.
We see here a typical instance of the mechanical theories of
physiological events of which the master Borelli was so prolific.

For a while Professor of Anatomy at Pisa, later on Bellini

iv] of Glands and Tissues, 111

became physician to Cosimo III. at Florence. He wrote several
books and achieved fame and fortune: but this discovery of
the urinary tubules, made in his teens, was his chief, perhaps
we may say his only valuable contribution to physiology, and
in this the hand with which he wrought was the hand of
Borelli.

Lastly it must not be forgotten that in 1654 Glisson, to
whom I have already referred, and of whom I shall have to
speak more fully in a subsequent Lecture, published his work
on the Liver. In that work he gave a very careful description
of the anatomy of that organ, which though set forth in some-
what cumbrous, academic fashion, made a valuable contribution
to our knowledge, especially perhaps in all that relates to the
distribution of the vessels. We at the present day call these
researches to mind when we speak of Glisson's capsule, a
structure which he was the first accurately to describe. This
is what he says: "This structure was wholly unknown to the
" ancients and therefore has hitherto been without a name. I
"was the first (unless I am mistaken) to discover it, which
"I did twelve years ago when, at the mandate of the College
"of Physicians of London, I delivered a course of public
"lectures, and in preparation of that course removed the
"parenchyma from the livers of a large number of animals."
And he describes his method of tediously scraping away the
parenchyma. So far however as the intimate structure of the
secreting substance of the liver is concerned he left much
untouched, much indeed that he could not touch, seeing that
he made apparently no use of the microscope. He admits that
the parenchyma of the liver is the principal part since all other
structures seem simply subservient to it, and speaks of it as
exercising a straining action, of serving the purposes of a filter;
but Vesalius had done this long before him. It strains off on
the one hand the bile, and on the other hand the pure blood ;
and the filtration or separation of the two humours takes place
he says in the following way : " It is very probable that parts
"or particles of which the parenchyma is composed are of
** different natures so as to be allied on the one hand to one of
" the humours to be secreted (the bile), and on the other hand

112 Malpighi and the Physiology [leot.

"to the other humour (the pure blood). Whence it comes
"about that those humours suit themselves to those parts
"with which they have the greatest likeness and affinity.
" And that is the beginning of the secretion of them. The
" particles for instance which have the greatest affinity to the
"bile humour attract this to themselves, and then pass it on
" to the first beginnings of the biliary duct. In like manner
"those particles whose business lies especially with the pure
"blood attract this to themselves, and then carry it to the
"capillary roots of the vena cava,"

Hence when during his stay at Messina Malpighi was
studying the structure of the viscera, the results of which
study he did not however publish until his return to Bologna
in 1666, he had before him the striking new discoveries of
which I have just spoken, namely the discovery of the pan-
creatic duct in 1642 by Wirsung, of the submaxillary duct in
1652-6 by Wharton, of the parotid and other ducts in 1661 by
Stensen, and of the structure of the kidney in 1662 by Bellini.
He was also acquainted with the distinction between con-
glomerate and conglobate glands made by Sylvius, as well as
with the researches of Glisson on the liver and of Stensen on
glands in general.

What use did he make of these, and how much further did
he carry us?

Malpighi*s book on the viscera contains an account of the
study of four organs, the spleen, the kidney, the liver, and the
cortex of the brain.

We may say at once that in his tract on the cerebral cortex
he shewed that he was not infallible; carried too far by the
enthusiasm for glandular structures which the works just
mentioned had excited, he maintained that the cortex of the
brain was also glandular; he described the superficial grey
matter as glands hanging on to the strands of the white fibres
like the fruit of the date palm.

In his tract on the liver he modestly says that Glisson had
left him little to say, and yet the little which he did say was of
prime importance. He for the first time shewed that the liver
was constructed after the fashion of a conglomerate secreting

iv] of Glands and Tissues. 113

gland, that its substance was arranged in small masses essen-
tially like those of which a conglomerate gland such as the
pancreas was made up; to these he gave the name of acini.
Henceforward the mystery which had for so long hung over the
liver was cleared away; the liver secreted bile after the same
fashion that the parotid and submaxillary glands secreted saliva.

This is what he says :

" Since in the higher, more perfect, red-blooded animals, the
" simplicity of their structure is wont to be involved by many
" obscurities, it is necessary that we should approach the subject
" by the observation of the lower, imperfect animals." He ac-
cordingly studies in the snail the organ " which by its position
**and the connection of its vessels obviously fulfils the nature
** and function of a liver." This he finds " to be divided into
"a number of lobules, possessing not so much a spherical as
"a conical outline.. Nor is Nature content to have made use
" of such a division merely ; but, in a most liberal manner, has
•'established a further division into very small parts, visible
" only by the aid of the microscope. For each of the lobules
"just described is made up of small rounded bodies, like berries
"(acini) crowded together after the fashion of a bunch of
"grapes, and connected with the whole lobule by means of

He traces out a similar structure in other animals, in fishes,
reptiles, mammals, and finally in man, pointing out that these
structural features had been dimly seen by others, as by Glisson,
who, most accurate observer though he was, was so carried
away by his preconceived idea of the continuity of the paren-
chyma of the liver, as to refuse to see what was clearly before
his eyes. And he thus sums up :

"In constructing the liver the following seems to be the
"constant method of Nature. The vessels in the liver are
"distributed in branches carried hither and thither in the
"common sheath observed by Glisson, in a manner I say
"similar to that which we see in the lung. Around the ends
"of each of the vessels, even the slender ones, are attached
"lobules maintaining for the most part a conical outline,
"not unlike that arising from the division of parts already

p. L. 8

114 Malpighi and the Physiology [lbot.

"described as existing in the lungs; and we may observe
** a similar arrangement in the pancreas and other conglomerate
" glands.

"These lobules are clothed with an investing membrane
"of their own, and are joined together by membranous ties
** carried across from one to the other, so that only very small
" intermediate spaces or clefts appear between the sides of the •
** lobules which are so adapted to each other that no interruption
" between them either great or small arises, the size, position
" and adaptation of the cones being changed as required. We
" have shewn the same thing more clearly in the lungs. It is
" to be observed however, that the outline of the lobules is not

"the same in all animals, but varies within very wide limits.

» » » » »

"The glandular acini of which each lobule is composed,
" since they have a special circumscription, possess an outline
"of their own, which is for the most part hexagonal or poly-
"gonal. Hence they necessarily are joined to each other by
" special membranous ties in addition to the vascular branches ;
"and certain interstices occur between them which are quite
" conspicuous in fishes and other lower animals, but are obscure
" in the higher animals.

" To each of these lobules, even to the very small ones, as
" may actually be observed or inferred from a variety of facts,
"are carried numerous branches of vessels. For the divisions
"of the vena cava, of the vena portse, and of the bile-duct
" ramify continuously throughout the whole mass of the liver,
" as Glisson, in that work of his on the liver which cannot be
"too highly praised, has very clearly shewn. In the lobules
"which constitute the outside surface of the liver, the blood
" vessel, spreading out from a centre ramifies in all directions
" over the whole periphery, sending forth bifurcating branches
"by which the whole lobule is irrigated. And the same can
" (not) be doubted concerning the deeper parts. For although
"the actual eye of sense cannot, especially in the higher
" animals, reach the extreme ends of the vessels which open
" on to the glandular acini, yet we may follow them adequately
" with the eye of reason. For the whole mass of the liver is

iv] of Glands and Tissues. 116

"composed of these two factors, namely, the glandular acini,
" and the different terminations of the vessels. Wherefore in
"order that some common result may issue from this, some
"intercourse between the glandular elements and the vessels
" must necessarily take place.

"Moreover, in the liver Nature follows this rule that the
"branches of the vena portae play the part of arteries, as m
"indicated by the complexity of their coats; and so closely
"is the vena portae associated and connected with the bile-
"duct that the small divisions of both of them are closely
"wrapped together in the same sheath."

He concludes that both observation and recuson shew that
the liver is to be regarded as a conglomerate gland, such as is
the pancreas. And "since it is a feature of conglomerate
"glands that they possess an excretory vessel of their own,"
as Sylvius and Steno have shewn, " since this is the rule of
" nature in the parotid, in the pancreas, in the salivary glands,
" the sweat glands, the lacrymal glands and others, since in
" these dispersed through their proper substance there may be
" seen a special vessel distinct from the other ordinary vessels;
" such as veins, arteries and nerves, a similar structure must be
*' looked for in the liver." He infers that the bile-duct is the
proper excretory duct of the liver.

He had to contend against a heresy recently put forth that
the bile was secreted, not in the liver itself but in the gall-
bladder by means of the blood vessels and membranes of that
organ, and that it was carried thence to the liver to aid in the
process of sanguification. Against such a view all the above
anatomical results afforded irresistible arguments; but he
clenched these by a vivisectional experiment. Laying open
a kitten, he tied the common bile-duct close to its entrance
into the duodenum, and by a median incision emptied the gall-
bladder. In a short time the common duct and the bile-duct
were filled with bile. He then put a ligature round the neck
of the gall-bladder ; the common duct and the bile-duct were
still full of bile, and when with his finger he tried to press
back their contents towards the liver, they returned with force
when the finger was removed.

8—2

116 Malpighi and the Physiology [lbct.

He thus concludes :

" Among various questions which arise out of the discoveries
"which have been described, two stand out prominent. By
"what mechanism is the bile separated in the glandular acini
"of the liver, and what is the use of bile in the economy?
" The illustrious Pecquet has made many deductions from the
" principles of mechanics concerning the former ; since, however,
"the structure of the acinus is so minute that it cannot be
"laid bare by even the very best microscope, we can only
"have recourse to hypotheses and to the working of similar
" mechanisms in attempting to explain this." And such a
labour he does not propose to take up.

As to the use of the bile he can only say "that it is
" probable that after the food has been triturated (in the
"stomach) juices of a different nature are poured upon it from
"the glands of the liver and from the pancreas, for a purpose
"not unlike that which appears in the cooking of food when
"out of sweet, sour, and salt things mixed together, a new
"composition and a new taste are developed. Let the wide
" industry of others carry matters further, I am contented to
"have described the simple and rude structure of the liver."

The description itself, however, was neither simple nor
rude. It brought clear light to what before was wholly dark
or, at least, most obscure ; and where Malpighi left the matter,
there it remained, with little change, until the present century.

In his tract on the kidney he went far beyond Bellini. He
shewed that in man at least the kidney really consisted of
several kidneys, and that the several constituent kidneys might
be distinguished as masses of Bellini's tubules arranged in the
form of pyramids, the pyramids since known as the pyramids
of Malpighi. He shewed how in each pyramid Bellini's tubules
ended in orifices at the summit of the papilla which formed
the apex of the pyramid, and further how in the cortex of the
kidney the tubules were not straight as Bellini had described
them, but curiously and irregularly twisted. Lastly he pointed
out how many at least of these tubules began as inflated
swellings or capsules, " round like the eggs of fishes," and how
these capsules contained a knot of blood vessels, and so hung

iv] of Glands and Tissues. 117

on to the small arteries as '' apples hang on to the branches of
a tree.*' And he stated his conviction that these capsules, which
have ever since borne his name, must play an important part in
the secretion of urine.

Thus in 1666 Malpighi had arrived at a clear conception of
the structure of the kidney. And the world had long to wait
for any further large addition to our knowledge on this score.
It is true that we owe a minuter knowledge of the distribution
of the renal blood vessels to the skilled injections of Ruysch,
who, bom in 1638 and called to the chair of Anatomy at
Amsterdam while Malpighi was at Messina, lived a life prolific
in work far on in the next century, until 1731, work which was
partly, and so far wrongly, directed towards undoing what
Malpighi had done, making the blood vessels the agents
instead of the aids of secretion. It is also true that Antoine
Ferrein, Professor at Montpellier and at Paris, made, nearly a
century later, in 1749, in company with many errors, and these
very great ones, a slight contribution to our knowledge when
he described the rays of straight tubules shooting up into
the cortex, since known as the pjrramids of Ferrein. Putting
aside however these two things, we may almost say that our
knowledge of the kidney remained where Malpighi left it,
until in the generation which has just passed away Bowman
took up the subject again.

Lastly, in his tract on the spleen, that organ to which in
the past so much honour had been paid, to which had been
attributed so many and such varied and important duties,
Malpighi brought into a region thick with the mists and clouds
of indistinct theories and speculation the dry light of exact
inquiry ; and the mists and clouds forthwith dispersed.

He gave a careful description of its structure, of its capsule,
trabeculsB and pulp, and of its blood vessels and nerves. The
trabeculse he at first suspected to be nervous in character, but
he soon recognised that in many animals they were muscular or
at least contractile. " The fibres" (i.e. the trabeculse), he says, **of
" the spleen are not, as I once thought, nervous but fleshy, so that
** by means of the external fleshy capsule and the fibres carried
** transversely fi:om it is formed a remarkable muscle com-*

118 Malpighi and the Physiology [lect.

" pressing the chambers of the spleen, in structure and fashion
"not unlike what is seen in the larger auricles of the heart."
He thus shewed that the spleen was not a gland, either
conglomerate or conglobate, but a contractile vascular organ
such as we now recognize it to be. But he also recognized the
possibility of changes of a peculiar nature taking place in the
spleen pulp filling up the chambers just alluded to, all the
more so since he was the first to observe small white bodies,
not unlike glands, attached to the blood vessels, bodies which
have ever since borne the name of Malpighian corpuscles. He
also called attention to the remarkable reticular sheath which
accompanies and wraps round the arteries as these plunge into
the body of the organ.

All these several fundamental discoveries were made before
he left Messina to take up his abode in his native city. During
his long stay in Bologna he continued to labour at anatomical
problems of physiological interest, and wrote important treatises,
such as those on the uterus, on hairs, horns, bone, on the
polypus of the heart, and especially one on the lymphatic
glands published by the Royal Society in 1689 {De atructura
glandularum conglobatarum, consimiliumqne partium); yet
none of these made known results at all equal in importance to
those on which we have just dwelt. Duiing this time his
intellectual strength was chiefly spent on researches not dis-
tinctly physiological, such as those on the anatomy of plants,
on the formation of the chick, on the natural history of the silk-
worm, and others.

The years slipped away without any striking event breaking
the even tenour of his way. His winters he spent in the city
busy with his jNTofessorial and professional duties ; his summers,
as we hav.e seen, were periods of repose and yet of labour in his
summer retreat. In 1662 he bought a villa and small estate at
Corticella in the neighbourhood of the city, and the possession
of a country house of his own led him, as years grew upon him,
more and more into rural retirement. In 1684 a great mis-
fortune befell him. His house in Bologna caught fire, his
microscopes were ruined and many of his precious manuscripts
were burnt. The loss of his furniture and such like things he

iv] of Glands and Tissues. 119

laughed at ; but the destruction of his papers filled him with
grief. Yet he did not despair, he persevered in labours of
inquiry. The old family feud continued to molest him up to
nearly his last days. In 1689, when he and his wife, both now
advanced in years and feeble in health, were residing almost
alone, or at most with the scantiest attendance, in their country
villa, some of the Sbaraglia party thought it no shame to dress
themselves up in grotesque costumes and make a burlesque
attack upon the dwelling. Not content with frightening the
infirm old man and his invalid wife, they attempted to injure
his property and even to destroy his papers. Happily they
were obliged to desist ; but the incident illustrates some of
the difficulties amid which Malpighi carried on his remarkable
labours. With a name honoured throughout the world, sur-
rounded by loving friends at home, stimulated and encouraged
by the letters of other friends at a distance, especially perhaps
by those of Bellini, having himself a character which would
wish to be at peace with all men, his long life was throughout
from time to time embittered by ignoble attacks taking origin
from a paltry domestic dispute.

In 1691 Pope Innocent XII., soon after he ascended the
papal throne, sent to Malpighi, whose worth he had learnt to
value during the time in which as Antonio Pignatelli he had
resided in Bologna, an invitation to come to Rome and be his
physician. Malpighi at first refused ; he was unwilling to leave
his beloved city, his friends, his studies, and the country seat of
which he had become so fond, and to take up his abode, now
an old man near his end, in a strange city. But the Pope
would not take a refusal, and in the end Malpighi, though
unwillingly, accepted the invitation.

He left Bologna amid demonstrations of affection, esteem
and regret, he was received at Rome with every possible
manifestation of respect. And here for a while he continued
the labours of his life. But not for long. Soon after his
arrival at Rome he began to lose colour and flesh and to
look ill. In July 1694 he had a slight apoplectic attack. From
this however he soon recovered ; but during his convalescence,
which he spent chiefly in preparing for publication the writings

120 Malpighi. [lect. iv

which, under the care of the Royal Society, saw the light as his
posthumous works, a heavy blow fell upon him, the death of his
beloved wife who had stood by his side for so many years.

On the 28th of November a second stroke of apoplexy
came upon him, this time heavy and fatal, and on the following
day he passed away. At the post-mortem examination a very
large effusion of blood was found in the right ventricle of his
brain. By an irony of fate the right kidney of him, who had
done so much to clear up the mysteries of renal structure, was
found to be marked with old standing disease ; it was largely
dilated, and indeed he had for most of his life suffered from
renal calculi.

It may be truly said of Malpighi that whatever part of
natural knowledge he touched he left his mark ; he found paths
crooked and h6 left them straight, he found darkness and he left
light. Moreover in everything which he did there is the note
of the modem man. When we read Harvey we cannot but
feel that in spite of all which he did, he in a way belonged to
the ancients ; while he was destroying Galen's doctrines he was
wearing Galen's clothes, and speaking with Galen's voice.
When we pass to Malpighi we seem to be entering into the
ways and thoughts of to-day. Doubtless Malpighi was reaping
what Harvey had sown; doubtless he was also reaping what
Galileo had sown; doubtless also the microscope gave him a
tool which none before him had possessed. It was just the
putting these three things together which parts him from the
old times, and makes him the beginning of the new.

All the deeper problems of physiology turn on the mutual
action of the tissues and the blood, as the stream of the latter
sweeps among the elements of the former. Harvey shewed that
the blood did sweep through the tissues, Malpighi shewed what
the tissues were and how the blood swept through them. And
thus the way was opened for those inquiries into the ways
in which the blood acts on the tissue and the tissue acts
on the blood, inquiries the results of which are the pride of
modem times and the hope of times to come.

LECTURE V.

VAN HELMONT AND THE RISE OF CHEMICAL
PHYSIOLOGY.

In the work of the physiologist of to-day the teachings of
chemistry are held, and rightly held, in high esteem. Though
many problems in physiology may still be regarded, and, it may
be, will always have to be regarded as purely physiological
problems, as problems to be solved in their own way and by
no other means, yet a preponderating number, perhaps also an
increasing number of the problems on which the physiologist
is to-day engaged, are at bottom chemical or physical problems,
problems to be solved by the application of chemical or physical
methods to the phenomena of living beings.

In a previous lecture I spoke of the influence on the
progress of physiology exerted by the new physical learning
which came into power in the early years of the seventeenth
century; it was then that physics and physiology touched
hands. I now propose to speak of the way in which chemistry
came to the aid of those who were inquiring into the problems
of life, and thus gave rise to the chemical physiology which we
know to-day.

The physiology of Vesalius and his school consisted as we
have seen of deductions from the data of anatomical arrange-
ments confirmed or corrected by experiments on living animals.
From time to time Vesalius made use of the growing mechanical
knowledge of his age, and we trace here and there the influence
of the as yet imperfect physical conceptions then dominant.
But of chemistry as we now know it there is hardly a word.

122 Van Helmont and the Rise [lect.

If you take up a text-book of modem physiology you will
find page after page occupied with chemical matters. In
some text-books digestion and its consequences take up so large
a space as to suggest to the reader that the stomach is the
larger part of man. It is not so with the writings of Vesalius.
In that chapter in the Fabrica of which I have spoken as his
compendium of experimental physiology, the whole of digestion
and nutrition is dismissed in almost a single sentence. " Though
" there is no diflSculty in examining living dogs at different times
" after they have been fed with the view of investigating the
" functions of the alimentary canal, yet we learn little more by
"vivisection than we do by the study of the dead body, as
" regards the function of the liver, spleen, kidney, or bladder.
"It may perhaps please one to excise the spleen, as I have
** done, the animal living many days afterwards."

There is, so far as I know, not a single reference in any
of Vesalius* writings to that study of the intimate nature of
things which under the name of chemistry, or rather of alchemy,
was beginning to stir men*s minds and which was pushing its
way into the art of medicine. The great anatomist would no
doubt have made use of his bitterest sarcasms had someone
assured him that the fantastic school which was busy with
occult secrets and had hopes of turning dross into gold, would
one day join hands in the investigation of the problems of life
with the exact and clear anatomy so dear to him.

Nor did Harvey any more than Vesalius pay heed to
chemical learning. His book on the heart contains no more
references to this than do the writings of Vesalius, and even
his work on generation expounds only the chemistry of the
ancients.

During the sixteenth century however and still more in the
seventeenth century there grew up side by side, but as yet apart
from the physiology on which we have so far dwelt, a know-
ledge having an origin quite separate from anatomy, and
indeed at first quite separate from the study of living things,
a knowledge of which subsequently every physiologist had to
make use. With this knowledge the men of the seventeenth
century of whom we have spoken, Borelli, Malpighi and others

v] of Chemical Phydology. 123

were not UDacquainted ; but as a rule the share which it had in
the guidance of their thoughts was a small one. To Borelli,
the spirit of inquiry as yet reigning in chemistry was so
diflFerent from that of the school of Galileo that though some
passages in his writings shew an insight into what chemistry
might ultimately accomplish, most of the chemical explanations
of physiological phenomena so far put forward were treated by
him with contempt. He saw bis way clear so long as he was
dealing with the size and shape of particles, and was loth to
leave these for unmeasurable and occult qualities. Malpighi
seems to have been in his younger days much drawn towards
chemical studies, but the more exact results of microscopical
inquiry soon carried him too far away from them. Stensen
more than any of the men whom we have mentioned in the
preceding lectures recognized the part which chemistry might
in the future play in the progress of physiology, but he did not
of himself contribute to the advance of the infant science.
Chemical physiology had an origin of its own and for a long
time advanced on a line of its own, separate from or even
antagonistic to other branches of physiology. To this we must
now turn.

At the close of the fifteenth century, in the year 1493;
according to some 1490, twenty years or more before
the birth of Vesalius, there was bom at the little town
Maria Einsiedeln near the Lake of Zug, in the Canton of
Schwyz, in Switzerland (whither to quite a late period
pilgrimages were made), one who, under the name of Paracelsus,
achieved a reputation more widely recognized in succeeding
times than that of any of the names which I have hitherto
mentioned, that perhaps of Harvey alone excepted.

His real name was Theophrastus Bombast von Hohenheim ;
to this others have added the words Philippus Aureolus; but
he always called himself Theophrastus von Hohenheim. His
father Wilhelm von Hohenheim was a physician at Einsiedeln,
and his mother had a position in the hospital there ; scandal
alleges that he was the natural son of a person of high degree.
The name Paracelsus is supposed by some to be a punning
translation of Hohenheim; others maintain that he himself

124 Van Helmont and the Rise [lbot.

adopted it as indicating that he was a greater than Celsus.
While he was quite young, in 1502, his father moved to Villach
in Carinthia and there he seems to have spent some of his early
days. He is said, at the age of sixteen, to have entered the
University of Basel, but soon afterwards to have become the
pupil of the Bishop Trithemius at Wiirzburg. Later on he
appears to have spent some time in some mines in the Tyrol
which were owned by the family Fugger. His personal
history, however, especially in his earlier years is wrapt in
much uncertainty.

It would not be fitting to the purpose which 1 have in
hand to dwell at length on the life and doings of this
remarkable, this picturesque man, whose name has become
a by-word for fantastic thought and even for charlatanry.
But for the understanding of the genesis of chemical physiology
it is necessary to say a few words about him.

To understand Paracelsus and his work we must, however,
go back to a man of still a generation before. In the latter
half of the fifteenth century there lived at Erfurt a Benedictine
monk, of whose personal life little is known, one Basil
Valentine, whose writings, the principal one of which was his
Currus triumphalis antimonii, teach us chiefly what can be
learnt about him.

He was one of the alchemists; but in addition to his
inquiries into the properties of metals and his search for the
philosopher's stone he busied himself with the nature of drugs,
vegetable and mineral, and with their action as remedies for
disease. He was no anatomist, no physiologist, but rather
what nowadays we should call a pharmacologist. He did not
care for the problems of the body, all he sought to understand
was how the constituents of the soil and of plants might be
treated so as to be available for healing the sick, and how
they produced their eflfects. We apparently owe to him the
introduction of many chemical substances, for instance of
hydrochloric acid, which he prepared from oil of vitriol and
salt, and of many vegetable drugs. And he apparently was
the author of certain conceptions which as we shall see played
an important part in the development of chemistry and of

v] of Chemical Physiology. 125

physiology. To him it seems we owe the idea of the three
* elements/ as they were and have been called, replacing the
old idea of the ancients of the four elements, earth, air, fire and
water. It must be remembered however that both in the
ancient and in the new idea the word * element * was not intended
to mean that which it means to us now, a fundamental unit
of matter, but a general quality or property of matter. The
three elements of Valentine were (1) sulphur, or that which
is combustible, which is changed or destroyed, or which at all
events disappears during burning or combustion, (2) mercury,
that which temporarily disappears, which is dissociated in
burning from the body burnt, but which may be recovered,
that is to say, that which is volatile, and (3) salt, that which is
fixed, the residue or ash which remains after burning.

To understand the beginnings of chemical physiology it is
important to remember the meanings attached to these three
words. In Valentine's mind, and long, long after him sulphur
did not mean the particular substance of a yellow colour, with
distinct atomic weight and other qualities which we now call
sulphur, but simply the constituent of any body, mineral,
vegetable, or animal, which disappeared and was apparently
wholly lost on burning. And so with mercury and salt.

To this conception of the properties of matter Valentine
added one concerning the forces which govern and determine
the phenomena of the universe, chemical changes included. He
spoke of an archceus, or of several archod, as being instruments
by which the Ruler of the Universe brought about events;
these were to him the embodiments of energy.

Paracelsus was early introduced into alchemical studies while
he was studying under the Bishop Trithemius ; he probably learnt
from him the doctrines of Valentine. These seem to have taken
firm possession of his mind before he entered upon the ordinary
medical studies of the time. It may be noted that those who
were engaged in the search for the philosopher's stone and on
the attendant chemical inquiries were, as a rule, not doctors,
and carried on their work apart from the universities and
medical schools. Many, very many of them were monks, or at
least ecclesiastics, and pursued their investigations in solitude

126 Van Hdmont and the Rise [lect.

and retirement. A certain antagonism arose between this
nascent science of chemistry and that older biological learning
which formed the basis of medical education. The latter was
the heritage of a long-established, powerful profession; the
former was the product of amateurs, of the efforts of scattered
independent workers, and as such was despised by professional
men.

We know little as to the extent to which Paracelsus carried
out his strictly medical, his anatomical and other studies ; but
it is clear that whether he learnt much or little the knowledge
which he thus gained was, even in view of medical practice, of
little account in his mind compared with the new chemical
science of which the doctors knew so little. He prized the
knowledge which had come to him through the alchemical
teaching of Trithemius, in the mines of Tjrrol and in his
subsequent wanderings as of more value than anything which
he could learn from the expositors of Galen. Hence when after
some years of travel, in which he is said to have wandered away
in the East as far as Samarcand, ever seeking it would appear
new chemical knowledge, he settled in 1527 as a physician
at Basel, it was not to be wondered that he came into conflict
with his orthodox brethren.

He may have been the turbulent, disorderly, noisy com-
bative fellow that he is represented to be: often deep in his
cups, and always, whether drunk or sober, ready to shout aloud
that his opponent was an ignorant fool and idiot, and that he
alone held the keys of truth. Even if he had not been this, if
he had been quiet, modest, and shrinking, he had laid hold of
something which the ordinary doctors of his time ignored and
despised, the beginning of that chemical knowledge which in
later years was to become one of the foundations of their science,
and the mainstay of their art. And this was enough to put him
in antagonism with them.

Driven away from Basel by their united opposition, he
wandered forth from place to place carrying with him his
scholars, his chemical apparatus, and his turbulent preaching
of his new doctrines. Now rising on the flood of success, with
what seemed the no less than marvellous cure of some sick

v] of Chemical Physiology. 127

great man whom the orthodox doctors had given up to death,
now plunged into some ignoble quarrel and hard pressed with
penury, never staying long in one spot, true to nothing but to
the assertion of his own ideas, he ended at Salzburg in 1541, just
as V^esalius was finishing his great work, his strange pilgrim life,
by what is generally credited to have been a violent death in a
drunken brawl.

The doctrines which he taught with such intemperate zeal
were as I have said in the main the doctrines of Valentine, but
enlarged, and developed by the new light which he had gained
by his own researches and studies. He discovered many new
chemical bodies, and introduced many new remedies. He had
a great hand in the spread of that drug, which perhaps more
than any one drug has influenced the fortunes of mankind,
namely laudanum, the use of which is Said to have been due to
him. He was emphatically not an anatomist, not a physiologist,
but a pharmacologist. He paid little heed to the doctrines of
Galen, and cared little or nothing for anatomy. He was a chemist
to the backbone ; and his pathology was based not on changes
of structure and their attendant sjnnptoms but on the relation
of diseases to drugs. He insisted that diseases ought to be
known by the names of the drugs which cured them, morbus
helleborinus, and the like ; in this he was a forerunner of an
errant school of therapeutics in modem times.

His physiology, if we may so call it, may perhaps as part of
his philosophy be briefly described as follows :

Nature consists of visible matter and invisible forces. The
visible matter is constituted of the three elements, sulphur,
mercury, and salt; and attached to matter are forces, or
perhaps we should say properties, by which changes of matter
are brought about. But over and above these material forces
or properties, matter is subject to and its changes are governed
by spiritual forces, prominent among which are the archosi, " the
" chief archcBus being that exalted invisible spirit, that occult
"virtue which is the artificer of nature in everyone."

All physiological processes, according to him, are chemical
processes governed by the archcms. In health, all the varied
chemical processes are rightly governed by the archams.

128 Van Belmont and the Rise [lect.

Death is the loss of the archceus, the natural chemical changes
being then left entirely to themselves. Disease is the failure
of the archceus to govern aright, and is often the result of
the entrance into the body of germs bringing about chemical
changes which the archceiLS cannot master.

From this basis of philosophy there naturally followed his
system of therapeutics, which consisted on the one hand in
drugs which by their chemical properties assist the archceus in
its struggles with chemical changes, and on the other in occult
invisible spiritual agencies, magnetic, astral and the like (for
the stars working through the archcei aflFect the chemical pro-
cesses of the body) which more directly join hands with the
archceus,

Paracelsus' doctrines as he put them forward had little or
nothing in common with either the Galenic teaching of the
day or the anatomical teaching of the succeeding age. They
stood outside these, and seemed to such men as Vesalius
and his followers the ravings of an ignorant charlatan.
Nevertheless after a time, after the lapse of nearly a
hundred years, they were taken up by a man, who so bandied
them that in a modified and developed shape they found
lodgement in ordinary medical teaching, and served as the
starting-point of that chemical investigation of the problems
of living beings which since that time and especially in these
later years has been so fruitful of results. As Paracelsus, with
the aid of some fifty years of increased knowledge, extended
and developed Valentine's ideas, so his doctiines were in
turn extended and developed with the aid of a hundred years
of increased knowledge (and those hundred years were as we
have seen rich beyond measure in intellectual gains) by van
Helmont, to whom we must now turn.

Jean Baptiste van Helmont was bom at Brussels in 1577,
some thirty odd years after Paracelsus* death, and more than
ten years after that of Vesalius. His father died when he was
three years old, and his mother, who was of one of the best
Belgian families, took much care of his education, sending him
at seventeen years of age to study philosophy at Louvain, which
university was still of great repute. The teachers there however,

v] of Chemical Physiology. 129

eminent though they were, failed to satisfy the intellectual
longings and the acute mind of the young van Helraont. To him
their sayings seemed empty words ; they made a great pretence to
learning, but in what they taught he could see no real truth,
could find no satisfaction for his mind. He refused to take the
degree of Master of Arts, as being a sign of scholastic frippery,
not of real knowledge. Anxious to satisfy his thirst for truth,
he turned to systematic botany, beginning, at that period, to be
seriously studied ; but this in turn he found to be as dry and
as unsatisfying as the herbaria which supplied its means of
study. He then tried law, but this he soon found worse than
even the others. He had almost reached the stage of Faust,

Habe nun, ach ! Philosophie

Juristerei und —

But he had not yet tried medicine. This he was led to do,
and in this he, for the first time, found what his soul desired.
I mention these earlier ventures of his because they are
indications of an acute active mind earnestly seeking after real
truth; and love of truth in spite of the somewhat fantastic
form which his ideas, after the fashion of Paracelsus, took in
his later writings was after all the key-note of his character.

He threw himself so heartily into his medical studies that
in 1599, at the early age of twenty-two, he took his Doctorship
of Medicine, and is said to have been appointed immediately
afterwards to deliver a course of lectures on surgery.

Wisely however he decided to travel, and the next four or
five years he spent in visiting difierent countries, Switzerland,
Italy, where he is said to have met Fabricius, France, and
England.

Returning home in 1605, he arrived in time to study the
great epidemic of plague then raging in Antwerp, and afterwards
settled for a while at Brussels ; later in 1609, having married
a rich heiress, he took up his abode in the neighbouring town
of Vilvorde. Here he remained for the remainder of his life,
practising to a certain extent as a physician, chiefly however it
would appear as a work of charity, for his means were ample,
but mainly occupied with carrying out chemical observations
and experiments. And here in 1644 he died.

F. L. 9

130 Van Helmont and the Rise [lect.

He published several books, the first in 1617 ; but his ideas
and doctrines are chiefly embodied in his work Ortus Medicince,
which however did not see the light until 1648, four years after
his death, being edited by his son.

He was as we shall see a devout Catholic, an obedient son
of the Church; nevertheless a work which he published in
1621, De Magnetica Vulnerum Curationey in which insisting as
Paracelsus had done on the potency of magnetic virtues he
seemed to explain away, on physical grounds, some of the
miracles, he came into conflict with the spiritual powers ; and
for some time during the latter part of his life was condemned
to imprisonment, though his own house was allowed to serve as
his gaol.

Van Helmont, as I have already hinted, was from a certain
point of view a Paracelsus, a modest, softened Paracelsus come
to life again, but come again to a quite diflferent world.

The medical studies, in which van Helmont first found
something solid to rest upon, were not the vague Galenic
teachings which were all that had been offered to Paracelsus,
but teachings based on the exact anatomical knowledge pro-
vided by Vesalius and his school, and on all which that
knowledge earned with it. So soon as he had graduated,
perhaps even while he was still a student, there came to him
as to all others in Northern Europe some of that new, exact
physical learning which was starting up in Pisa and in Padua.
While he was engaged in his own labours, long before he
had completed them, twenty years before his death, Harvey's
great work was open before him. He must have heard of
it ; but it may be doubted whether he ever read it. Certainly
he was not convinced by Harvey's arguments, for in his
writings, though he combats several of the Galenic doctrines
concerning the heart, he still accepts the Galenic view of the
passage of the blood from the right side of the heart to
the left through the pores of the septum. Still eight years
earlier, in 1620, there had appeared the Novum Organon of
Francis Bacon, which, though it probably had no influence
on van Helmont and most likely had never been seen by
him, was a characteristic product of the time and at least

v] of Chemical Physiology. 131

shewed the tenour of the thoughts among which he liv^d. It
is more than probable that he might ha-ve met Descartes, or
have read his Discours de la Mithode published in 1637.
And he must have been aware of the discovery of the lacteals
by Aselli in 1622.

The things of science were very diflferent in the first quarter
of the seventeenth from what they were in the first quarter of
the sixteenth century, in which Paracelsus lived. And much of
the new learning had sunk deep into van Helmont*s mind.
Yet for all that it was Paracelsus above all others who seems
to have influenced his thoughts. As you read his Ortus Medidnce
you are struck by the fact that while he rarely if ever mentions
the great names of which I have spoken, Vesalius and the
rest, the name of Paracelsus, and the mention of Paracelsus'
views occur again and again ; moreover the main doctrines which
he develops are Paracelsus' doctrines in a new dress.

Tet at the same time it must be confessed that as we read
van Helmont we seem to see two men, two intellects of very
diflferent kinds.

On the one hand we see a patient, careful, exact observer, a
child of the new philosophy, one who has entered fully into the
spirit of the new physics, who watches, measures and weighs,
who takes advantage of the aid of instruments of exact research,
who reaches a conclusion by means of accurate quantitative
estimations. On the other hand we see a mystic, speculative
dreamer, a philosopher in the old sense of the word, one weaving
a fantastic scheme of the powers and forces ruling the universe,
calling in the aid of invisible supernatural agencies to explain
the occun-ence of natural phenomena. And throughout the
whole of his writings is seen the continued endeavour to weave
his exact chemical physical knowledge and his spiritualistic
views into a consistent whole. Again and again he refers to
instances of the former as proofs or illustrations of the latter.

These two sides of van Helmont's character are not unfitly
indicated by the two words Gas and Bias, * two new terms * he
himself says, " introduced by me because a knowledge of them
(ie, of the things which they indicate) was hidden from the
ancients."

9—2

132 Van Helmont and the Rise [leot.

By * Bias ' he meant, so far as can be ascertained, the same
thing as the archcms of Paracelsus. It is true he uses the
word archcevs, as if he meant by it something different from
BlaSf but he often seems to use the one or the other indifferently.
In any case he believed as did Paracelsus in an invisible spiritual
or at least immaterial agency or energy which directed and
governed material processes and changes. He speaks of a Bias
meteoron which governs the heavens, and of a Bias humanwra
which presides over and determines all the functions of the
human body. The events of the human body according to him
as according to Paracelsus are governed by an archosus, or rather
by a hierarchy of minor archcei, all subject to and ministrants
of the chief archams. There is a Bla^ motivum presiding over
movements, and a Bla^ alterativum presiding over what we now
call metabolic changes ; and the Bias motivum is dual, for there
is a Bla^ which presides over voluntary and a Bias which
presides over natural movements. And there are other special
kinds of Bias.

But if by Bias van Helmont shews himself something not
very different from a Paracelsus redivivus, by Oas he clearly
disentangles himself from all the mystic Paracelsean lore, and
earns for himself the title of the first of modem chemists, and
at the same time the first of chemical physiologists.

By Oas he clearly meant, and by the introduction of the
new term indicates his appreciation of the discovery of, what
we now call carbonic acid gas, or carbon dioxide ; and as we
shall see the development of a great deal of chemistry, and
especially of the chemistry of living beings, has turned on
the nature and properties of gases.

It was in relation to this gas that he parts company with
Paracelsus. He argues that Paracelsus was wholly wrong in
maintaining that sulphur, mercury, and salt were the three
elements. There are he contends two elements only, air, that
is to say the natural atmosphere, and water. He spends much
time in proving that air and water can never be changed, the
one into the other, that they are distinct and never convertible,
that the vapour of water is something wholly different frx)m
real air.

v] of Chemical Physiology. 133

On the other hand by what he called water, he meant
everything which is not air; he insists that all things, plants
and animals, can be reduced to water, that they are in fact
water endued with certain properties.

" That all vegetables and flesh consist of water alone I can
"prove by experiment. Everything indeed if not directly, at
"least with the help of an adjunct, can be made to assume
" again the nature of water. All stones, rocks and mud, either
" of themselves, or with assistance, change into alkaline salt (sal
"alkali); and all sal alkali, fat being added, is reduced to a
"watery liquor which at length becomes plain and simple
" water."

Here is an example of the quantitative method by which he
carried out his investigations :

" That all vegetables are produced immediately and materially
" out of the single element of water I learnt by experiment. I
" took an earthen vessel in which I placed 200 lbs. of earth dried
** in an oven. I then watered it with rain water and planted in
" it a young willow weighing 16 lbs. After the expiration of
"five years this willow weighed 169 lbs. and some ounces.

"The earthen vessel which was always, when necessary,
"moistened with rain or with distilled water, was large, and
" was sunk in the ground ; and lest any dust carried by the air
" should be mingled with the earth, an iron lid coated with tin
" closed the mouth of the vessel. I did not measure the weight
" of the leaves which were shed in the four successive autumns.
'*At the end, I dried the earth in the vessel, and found its
" weight to be 200 lbs. less some two ounces.

" The 164 lbs. or so, of wood, bark, and roots (by which the
" older tree diflfered in weight from the young one) were there-
" fore derived from water alone."

Is not this a good experiment, one such as an experimental
agricultural station of to-day need not be ashamed of? It is
only the conclusion that is wrong. Would not van Helmont be
now delighted to hear that it was not water but gas, carbon
dioxide, which in the main accounted for the increase in weight?

He goes on to expound how out of many things can be
obtained, in various ways, a something which is like air, but is

134 Van JBelmont and the Rise [lect.

not air, not the air of the atmosphere. This appears when
wood is burnt, when the must of grapes or of malt ferments in
the making of wine or beer, and on other occasions ; and this
he calls * gas/

He gives it that name, because the sound is not so far from
that of * chaos,' the unformed womb of all things.

Here is an experiment giving a quantitative proof of the
existence of gas in wood or charcoal :

" Charcoal moreover, even if heated in a closed vessel for
"nine days in a burning furnace, though it is exposed to
"combustion — for the fire has access to the charcoal in the
"closed vessel just as it does when charcoal is burnt in the
" open — nevertheless is not at all consumed. It cannot be
" consumed because its effluvium is prevented. Charcoal there-
" fore, and we may say generally all things which do not directly
"change into water, and are not fixed, necessarily give forth
"the spirit of wood (spiritum sylvestre). Consider that of
" 62 lbs. of charcoal of oak, 1 lb. only remains as ash when it is
" burnt. The remaining 61 lbs. therefore consist of that spirit
" of wood which, even though the charcoal be exposed to fire,
" cannot escape from a closed vessel. This spirit, hitherto un-
" known, I call by the name of * gas.* ♦ ♦ ♦

" Many bodies indeed contain this spirit, and some are wholly
" changed into it. Not indeed that it is present in these in its
" actual state of gas, but as a condensed spirit, solidified to suit
'* the fashion of the body in which it resides ; and it may be set
" free by the action of a ferment as in wine or bread."

This idea of a ferment setting free gas by its action was one
of which, as we shall see, he made great use. He says :

" A grape uninjured may be dried and kept without change
"for an indefinite time; but if once its skin be broken, it
"presently receives the ferment of ebullition, and hence the
" beginning of change.

" The juice of grapes, apples, berries, honey, and even bruised
" flowers and twigs, a ferment having been laid hold of, begin to
" bubble and effervesce, whence gas.

" When I was a student, misled by the authority of ignorant
"writers, I thought that the gas of grapes was the spirit

v] of Chemical Physiology, 135

" of wine in the must ; but negative experiments shewed me
"that the gas of grapes and must was preparatory to the
" wine but not the spirit of wine (alcohol) itself.

"The history of gas is well shewn by gunpowder, which
" consists of saltpetre, sulphur and charcoal. When these are
" mixed together and ignited there is no vessel in nature which
" (if these were shut up in it) would not, on account of the gas
" produced, burst."

His gas he affirms is not air. " Some impostors think that
" gas is wind or air occluded in things, having been introduced
" into the mixture of elements at the origin of things." But
this is not so. Gas is really a form of water. "The gas
" of salts is water. That the gas of fruits is nothing but water
" follows from what I have already shewn, namely, that these arise
" from water. A dried grape, submitted to distillation, is thereby
" reduced by art to elemental water, whereas a grape fresh but
"injured gives rise to must and gas. Since therefore the whole
"grape in the absence of ferment is turned into water, but
" gives rise to gas whenever a ferment is applied, it follows of
" necessity that the gas is itself water."

Deeply impressed with this idea of the action of ferments,
van Helraont makes it the basis of his system of physiology.
Nearly all the writers before him had caught hold of the pheno-
mena of the fermenting wine-vat, as being, though mysterious
in themselves, illustrative of the still more mysterious pheno-
mena of the living body ; and the old idea of the physiological
spirits of the body, natural, vital and animal, was connected in
its origin with this same formation of alcohol, of spirits of wine
by fermentation. The anatomical school of Yesalius and those
after him, busy with other things, did not attempt to develope
the conception ; they, as we have seen, passed on one side of the
chemical events of the living body. Van Helmont was the first
to attempt a connected exposition of these matters. He was
doubtless well acquainted with the physiological and anatomical
teaching of the time. But in his writings he dwells very little
on these; he is chiefly concerned with the chemical events
which others had neglected.

His exposition of physiology is based on a theory of ferment-

136 Van Hdmont and the Rise [lect.

ations. The ordinary vinous feimentation gives him his initial
idea ; following this up, he regards all the changes in the body
(not digestion only but also all others including nutrition, im-
pregnation and even movement) as due to the action of ferments.
And he reconciles this view with his view of the influence of the
Bias or ArchamSy by the hypothesis that these spiritual agents
work not by acting directly on matter, but by making use of
the ferments, which are thus their servants or instruments. The
following is a brief sketch of his exposition of physiological events:

He assumes the current teaching of the day to be (1) that
the food absorbed from the stomach and intestine is in the liver
endued with natural spirits, (2) that in the heart the natural
spirits are converted into vital spirits, and (3) that in the brain
the vital spirits are converted into animal spirits. And indeed
this was still to a large extent the teaching of the day. It was
as we have seen the exposition given by Descartes even after
van Helmont*s death ; the influence of the Harveian doctrines
had not as yet made themselves fully felt.

All this current teaching, says van Helmont, is wrong.
There are not three conversions, three upward developments
only, but in reality six. And each of these upward steps is of
the nature of a fermentation ; he speaks of them as six digestions
or concoctions, by which the dead food becomes the living,
active flesh.

The first stage is the digestion in the stomach. It may be
noted that he wholly ignores saliva and the changes in the
mouth ; Steno and Wharton had not yet written. It is obvious
he says that in the stomach fSod and drink are converted into
chyle ; and this conversion takes place by means of a ferment.
But this ferment does not reside permanently in the stomach, is
not always there, for digestion is not continually going on in
the stomach ; the process is an intermittent one. The ferment
really comes from the spleen ; it is from the spleen that the
stomach draws all its energy. And in another part of his book
he dwells on what he calls the duumvirate, the dual reign of
the stomach and the spleen. He was still under the dominion
of the old traditions of the spleen ; he had not got so far even
as the clear-sighted Vesalius ; and Malpighi had not yet written.

v] of Chemical Physiology. 137

This ferment in the stomach is an acid ferment (questions
of acids, alkalis and salts were beginning to move the chemists
of the time) ; but the acidity is not the ferment itself, is only the
organ or instrument of the ferment. "If the ferment were
" only an acid, vinegar alone would be able to transmute a mass
" of bread and be sufficient for the transformation of all our
" food." He adds that " condiments help digestion, not because
"they add to the ferment, for a ferment can add nothing to
" itself, it is a specific gift of vital nature ; they simply prepare
" the food for the easier access of the ferment."

In this exposition of peptic digestion we recognize the
careful, exact observer ; for the above comes very near to the
doctrines of to-day, and even the idea about the spleen has
its modern analogue.

He then goes on to state that the acid chyle, passing into
the duodenum immediately acquires a saline nature, changes
from an acid into a salt, "just as vinegar by the addition of
nimium (lead oxide) is changed into an aluminous sweetness."
But this analogy is, he hastens to say, a lame oue. The change
in the duodenum is brought about * through a more excellent
vigour of transmutation.' The ferment actions of which he is
speaking are much more complicated than ordinary chemical
actions. It is, I may say in passing, worth while to note this
expression; it shews that van Helmont was nearer the truth
than some of those who immediately followed him.

This change in the duodenum constitutes van Helmont's
second digestion, and the ferment by which it is eflFected is
furnished by the bile ; he argues at great length that the bile
is not a mere excrement, but is or contains a ferment. And he
remarks in passing that the work of the acid ferment of the
stomach ceases when the chyle reaches the duodenum. " For
" every ferment dislikes to have as its allies things foreign to
"itself; it will not listen to the commands of strange masters,
" it refuses to play the thief and put its sickle into another's
"harvest." We repeat this saying of van Helmont's, when
to-day we teach that the pepsin of the stomach is destroyed in the
duodenum by the bile and pancreatic juice. Of pancreatic juice
van Helmont knew nothing, for Wirsung had as yet not written.

138 Van Helmont and the Rise [lect.

The third digestion to which this duodenal digestion, by
which as we sometimes now say acid ch)ane is converted into
alkaline chyle, is the prelude, is that of sanguification, which
beginning in the mesenteric veins, is continued in the liver,
and completed in the vena cava, a sanguification by which the
chyle is converted into blood, into crude blood, into cruor and
into serum, not yet into vivified blood ; the cruor will later on
become tliis vivified blood, the serum being used for the forma-
tion of urine and of sweat.

The ferment for this third digestion is furnished by the
liver, which thus supplies two ferments. One is carried to
the duodenum by the bile from the gall-bladder ; and it almost
seems as if van Helmont accepted the view that was held by
some that the bile was secreted by the gall-bladder and not by
the liver itself. The other descends from the liver along the
mesenteric veins. And he notes that the sanguification of
chyle, its conversion into blood being a more exquisite digestion
than the acid fermentation of food into chyle, takes place, not
like that in one wide open cavity but in a number of narrow,
and yet not too narrow passages.

It is worthy of notice that van Helmont, though well
acquainted as he obviously was with the medical literature of
the day, little as he might esteem some of it, and therefore
probably aware of Aselli's discovery, makes no mention of
lacteals. He regards all the chyle as being absorbed by the
veins ; and argues that since the chyle is not ready for absorption
until it has been prepared by the second duodenal digestion
there is no real absorption of food from the stomach.

He has his views about the mechanism of absorption. He
relates an experiment to shew that salts dissolved in water will
pass through a membrane such as a pig's bladder; and he
contends that absorption of chyle takes place partly in the
same way that salts pass through membranes, by diffusion as
we should now say, and partly by minute orifices in the walls
of the intestine, orifices which while open during life are closed
at death so that no absorption is possible from a dead intestine.

The refuse of the food, left after the absorption of the
nutritious chyle, passing along the intestine, meets in the

v] of Chemical Physiology. 139

caecum with a stercoraceous ferment by which it is converted
into faeces.

Such in brief outline is van Helmont's story of what even
now-a-days we sometimes call primary and secondary digestion.

The fourth digestion takes place in the heart and arteries.
By this elaboration the darker and thicker blood of the vena
cava becomes lighter in colour and distinctly volatile. By this
he obviously means the change from venous to arterial blood.
But he does not very clearly distinguish between this fourth
digestion and his succeeding ^/ifA digestion^ "which changes the
blood of the arteries into the vital spirit of the archceus.'' He
distinguishes between the crude blood (cruor) supplied by the
liver and the vitalized blood (sanguis) distributed by the heart
through the arteries.

" I never could satisfy myself/* says he, *' that there was any
"spirit in the crude blood (cruor) coming from the liver,
" though this had already acquired its own grade of perfection
"after it had left the mesentery. The crude blood from the
"liver has always seemed to me mere material for use; it
"ought not to be considered as perfect vital blood."

His view seems to be that by the time it reaches the
arteries the crude material blood has become vitalized blood,
through the presence of the spiritus vitalis. This spiritus is of
the nature of or acts after the fashion of a ferment, it multiplies
itself as a ferment does. It is always present on the left side
of the heart, in the arterial blood of the left ventricle, and some
of it is drawn through the septum, from the left side to the right
by minute pores which are too minute to allow blood to pass.

" Some of this spiritus," says he, " this ferment, thus drawn
" through the septum begins to multiply even on the right side
" of the heart. The right side of the heart labours incessantly
"for no other end than that it should draw a little spiritus
"from the left side across the septum of the heart in order
"that the crude blood in the vena cava close to the heart
"should by the participation of that spiritus at once begin
"to be vivified."

Apparently the fourth digestion is only the beginning or a
part of the fifth digestion, which as a whole consists in the

140 Van ffdmont mid the Rise [lect.

vivification of the blood, the conversion of crude into vitalized
blood by the addition and influence of the spiritus vitalis, always
present in the left ventricle, always subject to multiplication
and increase.

Two points may be noticed here. One is that van Helmont
came very near to and yet wholly missed the use of air in
breathing. The other is his singular clinging to the passage
through the septum.

We have seen how,. in spite of the direct evidence of their
senses, men clung for centuries to the view that the blood
passed through the solid septum of the heart, from the right to
the left ventricle. In spite of Servetus* stout assertion that
such a passage was impossible, in spite of Vesalius' biting
sarcasms, in spite of Columbus and Csesalpinus the view
still held its ground ; it gave way before Harvey, not because
Harvey like those before him denied it but because he
shewed a better way. Van Helmont, Harvey's contemporary,
bom the year before him and dying twenty-three years
before him, had not, as we have seen, profited by what
Harvey had done; he still believed that the blood passed
through the septum from the right to the left ventricle. He
added to the old view, a new one, that the fermentative spirit
which vitalized the blood passed also through the septum, but
in the contrary direction, namely from left to right. And he
argued that the pits in the septum, being conical in shape with
their narrow apices abutting on the left ventricle, and their
broad bases on the right ventricle, were so constructed in order
that they might prevent the return of the blood itself from the
left side to the right though they allowed the passage of the
more subtle spirit. The story forms an odd page in the
history of human thought, a page odd but full of warning.
When we examine our own views to-day about this matter and
that, are we sure that we are not asserting that things are
passing through a septum though our senses shew us that there
are in it no channels through which such a passage can take place ?

And now comes a remarkable generalisation, by which
van Helmont leaps ahead, and anticipates conclusions which
were not reached until many a long year after him.

v] of Chemical Physiology. 141

" The sixth and last digestion takes place in the kitchens of
" the several members, for there are as many stomachs as there
"are nutritive members. In this sixth digestion a spiritus, a
" ferment innate in each place cooks its food for itself." In the
language of to-day, all the tissues live upon the common blood,
and the power of assimilation lies in the tissue itself; it is the
tissue and not the blood which primarily determines assimila-
tion, the qualities of the blood have only an indirect influence.
" A vein," says van Helmont, meaning probably an artery, " may
"be considered as a vessel containing aliment prepared for
" the kitchens of the tissues, but it is not their kitchen. Each
" tissue maintains its own individual kitchen within itself."

He gives as an instance the nutrition of muscle. Accepting
the as yet common view (Stensen and Borelli had not yet
written) that muscle consists of an inactive, passive, non-con-
tractile part, the ' caro,' or flesh, and the active contractile part,
the fibres, van Helmont suggests that the crude parts of
blood can directly, without elaborate nutritive action supply
the * caro,' the flesh, which therefore can at any time increase
and grow in a vegetative manner, but that the fibres are nourished
by the vivified blood, through the activity of the tissue ferments,
and the growth of this, the active part of the muscle, is therefore
subject to the laws of life.

A corollary to this view of the sixth digestion, of the action
of the individual ferments of the several tissues is of no little
importance ; it led van Helmont to a position far in advance of
his peers.

"I make," says he, "no distinction between vital and
" animal spirits. The same blood with the same vital spirits,
" vitalized blood (arterial blood as we should say), is carried to all
" the tissues. The boat has only one rudder, each tissue lives
" upon that blood, exercising its own functions, the brain and
" other nervous tissues behaving in this respect like the rest of
" the tissues. As the spiritus, the so-called animal spirit, does not
" difier specifically in itself in the several organs of senses and
"instruments of movement, though the senses and the movements
" diflfer among themselves, so it is unnecessary to suppose an
" animal spirit apart from the vital spirit of the vitalized blood."

142 Van Hdmont and the Rise [lect.

So far I have dwelt upon van Helmont's work on what we
may call its rational side. What I have briefly described
constitutes a general exposition of the main facts of chemical
physiology, as van Helmont conceived them, and, as we have
seen, many of his conclusions were based on careful observations
and indeed on experiment. That exposition exerted a great
influence on investigators coming after him. In the first place
it shewed that many of the problems of the living body were
chemical problems to be solved by chemical knowledge, not
problems of a mechanical nature only, not problems to be
solved by the experimental verification of a suggestion offered
by anatomical arrangements. In the second plcice it drew the
attention of inquirers to the fact, which experience has shewn
to be an undoubted fact, that a large number of the processes
taking place in the living body are more or less akin to the
process by which yeast produces alcohol, as in wine making or
brewing, and therefore may be spoken of as fermentations.
This idea of the fermentative nature of the changes taking
place in the living body was as we have said an old one, it had
been preached by Paracelsus; but its definite introduction into
physiological thought is due to van Helmont. The authors
coming afterwards who dwelt on the subject all acknowledge
their indebtedness to him. In the third place his discovery of
carbonic acid gas, and of other gases, for he recognised that all
gas was not alike, that some gas for instance was inflammable,,
was a chemical discovery of prime importance, though the
value of the discovery did not become apparent until after the
lapse of many years.

But to judge by his writings van Helmont was at heart
more pleased with his Bias than with his Gas. In the ex-
position of which I have given an account there are repeated
interpositions, which I have omitted, numerous references to the
action of this or that bias or archseus. And any attempt to
picture van Helmont's mind would be incomplete without at
least some few words about his views as to the relations of the
archsBus, and so of the phenomena of the body, to what he calls
the sensitive and motive soul, the anima sensitiva motivaque.

"This sensitive soul belongs to man alone; for speaking

v] of Chemical Physiology. 143

"truly and thinking correctly, we must say that there is no
" soul residing in plants and in brute beasts. These possess
" only a certain vital power, which we may perhaps regard as
" the forerunner of a soul. The sensitive soul as it exists in
"man takes to itself the reins of that forerunning governing
"vital power, which thus melting into the archseus submits
" itself to the sensitive soul."

The sensitive soul is the prime agent of all the acts of the
body, the archaeus being its servant, the minor archaei also its
servants, and the ferments the instruments in turn of the archaei ;
it is this which is, among its other services, the prime cause
of the vital spirit which in the heart vitalizes the blood.
Though it carries out the sensations and movements of the
body by means of the brain and nerves its actual throne is in
the pylorus ; it resides in the orifice of the stomach. He gives
various reasons for this conclusion; among others the facts
that a great emotion is always felt at the pit of the stomach,
and that a man may have his head blown oflF by a cannon-ball
and yet his heart will go on beating for some time, whereas a
severe blow at the pit of the stomach will stop his heatrt and
take away his consciousness at the same time.

But the throne or temple of this sensitive soul is of a
peculiar nature. It is in the archaeus of the stomach that the
soul dwells; "there it sits and there it abides all life long."
" Not that the sensitive soul dwells in the stomach as in a sack,
" in a skin, in a membrane, in a bag, in a prison or in a shell.
" Nor is it confined to that seat after the fashion of things shut
" up in a purse. In a wholly peculiar manner is it present, in a
" point centrally, in an atom as it were, in the middle of the
"thickness of a mere membrane. Though it is placed in a
" locality, it is nevertheless not there in a local manner. For it
" is a light, and there is in the universe nothing so much like it
" as is the light of a candle; it is present in the stomach in some
" such way as light is present in a burning wick. But when I
" call it a light, I do not mean a burning, heating light, the cause
" of the heat of the body, for the heat of the body is merely
" the product of life, of vital actions, and is not life itself"

This sensitive soul is mortal, and in man, in his present

144 Van Helmont. [lect. v

state, coexists with the immortal mind, Tnens immortalis, the
two being connected in a peculiar way. " The sensitive soul is
" as it were the husk or shell of the mind, and the latter works
" through it, so that at the bidding of the mind the soul makes
" use of the archaeus whether it itself will or no."

" Before the Fall of Adam man possessed only the immortal
" mind which acted directly on the archaeus, and while this was
'* the case, while the immortal mind discharged all the functions
"of life, and the sensitive soul as yet was not, man was im-
" mortal, and the shadows of the brute beast did not blur his
" intellect.

"At the Fall God introduced into man the sensitive soul,
"and with it death, the immortal mind retiring within the
"sensitive soul and becoming as it were its kernel."

In thus speaking of these speculative flights of van Helmont
by which he brought his chemical views as to the nature of
man into harmony with the teaching of the Church, of which,
in spite of the heresy attributed to him, he was a devoted
son, I may seem to be travelling away from the proper
province of physiology. And yet this theory of the sensitive
soul did definitely enter into subsequent physiological thought.
Both parts of van Helmont's teaching left their mark on suc-
ceeding inquiries and thought. The influence of his doctrine of
fermentations may as I have just said be traced down even to
the present time ; but that doctrine was early stripped of its
archseal and other wrappings and soon took on the form of a
sober chemical knowledge.

The doctrine of the sensitive soul was also taken up by
some of his successors ; it appeared and reappeared at intervals,
now in more or less its original, now in a modified form. And as
we pass in review the succession of opinions as to the ultimate
causes of the phenomena of living beings we may trace a
genetic bond between van Helmont's picturesque and vivid
idea of a sensitive soul, and the paler, fainter views of a vital
principle held by some at the present day.

LECTUKE VI.

SYLVIUS AND HIS PUPILS. THE PHYSIOLOGY OF
DIGESTION IN THE SEVENTEENTH CENTURY.

I PROPOSE to devote the present Lecture to an account of
some men of the seventeenth century who may be regarded as
the successors of van Helmont in chemical physiology, at least
in that part of it which concerns digestion. But, before doing
so, I should like to turn aside for a while to say something
about a man, who, in the very early years of that century,
though he did not deal much with either the new chemical or
the new physical ideas, yet by applying the chief instrument of
physical inquiry, namely exact measurement, to the determina-
tion of chemical data opened up a line of inquiry which, unknown
before him and not greatly used in the times after him, has in
these later years been made to produce most valuable results.

Of the life of Sanctorius Sanctorius we know very little.
He was bom at Capo d' Istria in 1561, he studied and
graduated at Padua, and after travelling a good deal practised
for some time in Venice. He was later on called to be
professor of theoretical medicine in the University of Padua,
where he gave a discourse in 1612, and where he achieved
much fame, drawing many students to his lectures. After a
while however he withdrew again to private practice in Venice,
in which city he died in 1636.

In 1614 he published at Venice a small book entitled

Medical Statics, which subsequently passed through many

editions and was translated into several languages. It is

composed of several hundred short aphorisms, dealing with air

p. L. 10

146 Sylvius and his Pupils. [lect.

and water, with food and drink, with sleeping and waking and
other like topics. Each aphorism is a deduction from facts
determined by most careful measurements of the weight of
his body at diflferent times, of his food and of his excretions.
But he gives no account whatever of his experiments; in
striking contrast to many a modem memoir which seems in
great measure hardly more than a transcript of laboratory
notes, or at least consists in large part of detailed * protocols '
of experiments, Sanctorius' work gives only the bare con-
clusions. He merely describes in a very general way the
method by which he arrived at his results. He had constructed
a chair suspended to a steelyard, so that he could, using this
as a balance, accurately determine his body-weight, at various
times and under various conditions; and his book contains a
quaint picture illustrating how he weighed himself before and
after a meal. By this means he was able accurately to measure
the loss of weight to his body by insensible perspiration. As
he says in his Preface, " It is a new and unheard of thing in
"Medicine that anyone should be able to arrive at an exact
"measurement of insensible perspiration. Nor has anyone
"either Philosopher or Physician dared to attack this part of
"medical inquiry. I am indeed the first to make the trial,
"and unless I am mistaken I have by reasoning and by the
" experience of thirty years brought this branch of science to
" perfection, which I judged more advisable than to describe all
" the details of my inquiry."

In his aphorisms he occasionally gives us glimpses of his
experimental results, as when he says, " If the food and drink in
" one day amount to eight pounds, the insensible transpiration
" will generally amount to about five pounds " ; but as I have
said the book consists in the main of deductions concerning
changes taking place in the body as the result of this or that
condition, the nature of the changes being inferred from data
furnished by the amount of the insensible perspiration in
relation to the weight of the food and drink, of the sensible
evacuations and of the body. Sanctorius thus stands out as
the forerunner in the early years of the seventeenth century of
that statical method of physiological inquiry which during the

vi] Sylvius and his Pupils. 147

latter half of the nineteenth century has produced such useful
results. But he cared more for practical guidance than for
theoretical conclusions. He regarded his balance as a means
of helping a man * to live according to rule.* He proposed that
each meal should be taken sitting in his chair with the steel-
yard so adjusted that by the descent of the chair the diner
should be warned that the predetermined weight of food had
been swallowed. He was obviously a singularly original man ;
we learn for instance that he invented a thermometer for
measuring the heat of the animal body, and an instrument for
measuring the movements of the arteries.

We must however now return to the successors of van
Helmont.

In 1614, the year before van Helmont wrote his first book
and fourteen years before Malpighi*s birth, there was born at
Hanover of a good family one Frangois De le Boe or Dubois,
better known perhaps by his Latin name as Franciscus Sylvius.
He is the second prominent man of that name in the history of
physiology, the first being Jacobus Sylvius of Paris, in the
sixteenth century, the teacher of Vesalius. Though a man
of a wholly different type of intellect from van Helmont,
Sylvius appears in the history of physiological thought as
his legitimate descendant.

After studying at S^dan, at Basel, where in 1637 he took
his degree, and elsewhere, and after a stay of some years at
Amsterdam he became in 1658 Professor of Medicine at
Leyden, and there for many years exerted a most powerful
influence until his death in 1672.

In order to understand the importance and bearing of his
phyisiological and medical teaching, the nature of which may be
learnt from his many medical and physiological writings, it
must be borne in mind that he was not only a physician and a
physiologist, but also distinctly and clearly what we should now
call a chemist. He published many purely chemical works. He
persuaded the Curators of the University of Leyden to build for
him a ' Laboratorium, as they call it ' ; this seems to have been
the first University Chemical Laboratory.

Like Glauber, an older man, bom in 1604 and dying in

10—2

148 Sylvius and his Pupils. [lect.

1668, whose name is perpetuated in his sal mirabile, Glauber's
salt, sodium sulphate, and who though he made no marked
contribution to physiology, largely increased the chemical
knowledge of his time, Sylvius devoted much energy to the
study of salts. He probably owed much to Glauber, who
appears to have been one of the first to lay hold of the idea of
chemical affinity. But in any case Sylvius leamt to recognize
the nature of many salts as the result of a union of acids with
bases. He was the first to prove the presence of volatile alkalis
in plants. And it is perhaps mainly by the increased knowledge
of the various salts, and their composition, that his chemical
science is in advance of that of van Helmont, who died just
about or rather just before the time when Sylvius began to write.
If he was like van Helmont in being a chemist and in
looking at the phenomena of life from a chemical point of
view, and if he followed van Helmont in explaining many of
the events of the living body as due to fermentative processes,
successor, and in this respect may be regarded as van Helmont's
he dififered from him widely in almost every other respect.
Van Helmont paid little heed to that part of physiology
which is derived by deductions from anatomy, by experiments
on animals or by the application of mechanical principles;
Sylvius was well versed in all these things and wrote well
on the circulation of the blood and on the mechanics of
respiration. Harvey's teaching had apparently no influence
on van Helmont; it entered largely into Sylvius's thoughts,
and indeed it was chiefly through his advocacy that the
Harveian doctrines became established in Holland. Van
Helmont's mind was a double one, bent on the one hand
on exact careful experiment, turned wistfully on the other
hand to mystic speculations about invisible agencies and
spirits. Sylvius shared the former mental attitude ; the latter
was wholly foreign to his character. Van Helmont was es-
sentially an inquirer, most of his time was spent in his own
home, pursuing his own researches ; he cared more for fol-
lowing out his own ideas than for influencing the opinions
of others. Sylvius was essentially an expositor; his own
special contributions to the advancement of physiological,

vi] Sylvius and his Pupils. 149

as distinguished from chemical, knowledge were unimportant.
He was the discoverer of no new striking piece of physiological
truth, unless perhaps it be the distinction between conglome-
rate and conglobate glands, to which we have already referred,
and we owe to him it is true and not to his older namesake,
the aqueduct of Sylvius ; but the new things which he made
known were in the main chemical. Yet he occupies a not
inconspicuous place in the history of physiology on account
of his power and enthusiasm as a teacher. He became the
founder of a school.

We may infer something about the influence of Sylvius as
a teacher and about the scope of his teaching from what his
brilliant pupil Stensen says of him. Towards the end of his
larger treatise on muscle, Stensen, treating of what yet re-
mained to be learnt about muscle writes as follows: —

" No one as yet, so far as I know, has so joined Chemistry
"to Anatomy as to have clearly and distinctly explained, not
"by deductions from the doctrines of the schools but by
"following up the indications of Nature, in what respects
"muscle tendon and bone agree and in what they differ.

"My most eminent teacher Sylvius has laboured in this
"way with happy results, in respect to the humours of our
"body; and, if I remember rightly, I have often listened to
"him while he led by the same spirit of inquiry discoursed
" also concerning the nature of tendons and of bones. But that
"eminent man although he has done much in this branch of
" knowledge is, lest he might seem to sacrifice the public weal
" to his own glory, in the habit of daily assuring his pupils
" that he has not been able to accomplish everything. Hence
" he expounds, in the shape of views and speculations, matters
" concerning which he has not yet arrived at a clear and definite
"result, and thus he stimulates others to inquiry, supplying
" them at the same time with problems to begin with."

We learn from this that Sylvius had his mind open towards
all the chemical problems presented by the human body, but
that he busied himself chiefly with, and was most successful in,
the study of the fluids of the body, the blood, the lymph and
the several juices or secretions.

150 Sylvius and his Pupils. [lbct.

Sylvius as I have said followed van Helmont in considering
a large number of the changes taking place in the living body
as being of the nature of fermentative processes ; but his idea
of fermentation was a different one from that of van Helmont.
The latter taking vinous fermentation as the type saw in the
ferment which produced the change a subtle agency, having
characters of its own, one whose effects were wholly different
in kind from ordinary chemical events, from the result for
instance of adding a base, such as lead oxide, to an acid,
such as vinegar. The action of the ferment was in van
Helmont's eyes of a more exquisite nature than a simple
chemical change; the bubbles of gas which appeared in the
fermenting vat were incidental things, not features essential
to the action of the ferment. Sylvius saw nothing of all these
subtle distinctions. To him the rising of the bubbles of gas,
without the intervention of an extrinsic blast of air, seemed to
be one of the essential facts of fermentation ; and since he saw
the same spontaneous escape of gas when an acid was poured
over an earth or a salt, when oil of vitriol for instance was
poured over chalk, he concluded that the two processes were
identical in kind. Hence, though he continued often to use
the word 'fermentation,' he more often used the word 'effer-
vescence,' and at times seems to use the one or the other quite
indifferently.

Vieussens, who in addition to the researches in anatomy
which have handed down to us the terms * valve of Vieussens '
and 'annulus of Vieussens,' busied himself with chemical
matters, writing in 1688, De natura etc, Fermentationis, thus
formally defines the various kinds of fermentation:

*' Fermentation is the adventitious and expansive movement
"of heterogeneous parts and of insensible fermenting bodies
"excited without sensible cause, which, when it is vehement
'*or of long duration, brings about an essential change or a
"conspicuous alteration in the fermenting bodies themselves.

" Latent fermentation, than which nothing is more common
" alike in the works of nature and of man, is an adventitious
" and expansive movement of heterogeneous parts and insensible
"bodies excited without sensible cause, which, when it is

vi] Sylvius and his Pupils. 151

** vehement or of long duration brings about an essential change
** or a conspicuous alteration in the fermenting bodies themselves
" and is excited so gradually and in so hidden a manner that
" while it is taking place it can not be detected by the senses,
" and hence is only recognised by the effects which in a given
" time it produces.

" Of this kind is the movement of the particles of a mass of
" dough which is beginning to ferment, but which so gradually
"liquefies and swells that the change which it is undergoing
" is only recognized when after some time it becomes softened
" and expanded.

"Sensible fermentation is the adventitious ♦♦♦♦♦♦
" bodies themselves and is recognized by the senses so soon as
" ever it begins. Such is the fermentation which is brought
" about when water is poured on quick-lime, or spirits of vitriol
" is mixed with oil of tartar.

" Vehement fermentation is the adventitious ♦♦♦♦♦♦
" sensible cause, which quickly brings about an essential change
''or a conspicuous alteration in the fermenting bodies them-
" selves and is produced with a certain impetus and indeed
"sometimes with considerable tumult. Of this kind is the
" movement which is observed when spirits of vitriol is poured
"on oil of tartar or water on quick-lime.

"'Moderate fermentation is the adventitious ♦♦♦♦♦♦
"which brings about an essential change or a conspicuous
" alteration in the fermenting bodies themselves gradually and
" without a rush, and with a certain buzzing only (fremitus) or
" without any noise or buzzing.

" Of this kind is that movement which must or wort, as
"for instance that of beer, treacle and things of that kind,
"undergoes when it ferments, and which takes place with a
"certain buzzing.

" Hot fermentation which properly and deservedly gains the
" name of fermentation is the adventitious ♦♦♦♦♦♦ in the
" fermenting bodies themselves, and is accompanied by or quickly
" acquires heat. Such is that which is observed when vinegar
" is mixed with quick-lime, which indeed is accompanied with
"fire and flame and therefore heat.

152 Sylvius and his Pupils. [lbct.

" Gold fermentation is the ♦♦♦♦♦♦ and is produced
"without any heat. Of this kind is that when coral is dis-
" solved in vinegar."

This confusion of fermentation, properly so called, with the
eflfervescence due to the escape of gas from simple direct
chemical action, though undoubtedly a retrograde step, may
be regarded with leniency when we reflect that it was only one
of many indications of the special attitude of Sylvius's mind,
through which, though he went too far, he did good service by
shewing that the importance and pertinency to physiology of
van Helmont*s chemical views might be recognized without
accepting his spiritualistic speculations.

Sylvius followed van Helmont in so far as the latter in-
sisted that many of the phenomena of the living body were to
be explained by the help of chemical science as the outcome
of chemical processes, a view which physiologists had before
van Helmont too much neglected; but he refused to follow
him in regarding chemical changes as mere instruments in
the hands of occult spiritual agencies. On the contrary he
boldly asserted that the chemistry of living things was the
same as the chemistry of so-called dead things, that what took
place in a live body was the same as that which might be made
to take place in a flask in the laboratory. And filled as his
mind was with the striking results which he had obtained in
the laboratory as he worked with salts, with acids, and with
bases, he jumped to the conclusion that the chemistry of the
living body was of the same order, and that an adequate
knowledge of acids and alkalis was the key to the interpretation
of the problems of life.

In taking up this position he performed at least one useful
task, he brought the chemical investigation of physiological
problems into line with the mechanical and physical investiga-
tion of them. The spiritualistic fancies of van Helmont, and
still more the earlier ones of Paracelsus, had had the tendency to
make men think that chemical inquiry in contrast with physical
inquiry was in some way necessarily bound up with speculations
about in^dsible agencies of a spiritual kind ; and this doubtless
was more or less a bar to men of sober and exact thought

vi] Sylvius and his Pupils. 153

entering upon that line of inquiry. To Sylvius at least is due
the credit of shewing that there was no such necessary con-
nection between chemistry and spiritualism ; that on the
contrary the newer chemistry in its attempts to solve vital
problems trod the path of the most naked materialism. It is
probably to his thus opening up a line of inquiry into chemical
physiology free from all taint of mysticism that the great
influence which as a teacher he undoubtedly exercised was
largely due.

Sylvius had the advantage over van Helmont of the know-
ledge of three important discoveries which were not made until
after the latter's death. Van Helmont knew only of the gastric
juice, the acid ferment of the stomach, and of bile as digestive
juices ; for we may omit his stercoraceous ferment of the csecum.
Sylvius knew of others. We have already seen that in 1655
and 1661 Wharton and Stensen discovered the submaxillary
and parotid ducts. On the importance of these two discoveries
with reference to the physiology of secretion I have already
spoken ; they were still more important as regards digestion.
Stensen paid little attention, and Wharton hardly any at all
to the digestive uses of saliva; but Sylvius seized at once on
its importance, and as we shall see attributed to it very large
powers.

He was also through the investigations of a pupil of
his led to recognize the possibly great uses of another digestive
juice. Wirsung had we have seen discovered in 1642 the
pancreatic duct, and appears to have observed the pancreatic
juice; but he did not pursue the subject, and indeed his
discovery remained barren until one of Sylvius' scholars took
the matter up. The work of the latter is so interesting an
example of the physiological experiments of the time that I
venture to speak of it in some detail.

Regner de Graaf, bom in 1641 at Schoonhaven in Holland,
of a good family, studied under Sylvius at Leydeo, and after
graduating and travelling, practised for some years at Delft,
where he died in 1673 at the early age of 32, having in the
previous year refused to succeed to the chair at Leyden, just
vacant by the death of his late master Sylvius. While at Delft

154 Sylvitis and Ms Pupils. [lbct.

he published some remarkable works on the structure of the
generative organs, and described the follicles in the ovary
which have ever since been known by his name. It was
however while a student at Leyden under Sylvius, in 1664, as
yet a youth of 23, that he made an investigation on pancreatic
juice, published under the title of Dispiitatio medica de natura
et usu sued pancreatici.

In this tract after relating several unsuccessful attempts by
various methods at obtaining the juice he tells us how he hit
upon the right one. He made use of the quill of a wild duck,
which he says may be got longer and thinner than the quill of
any other bird. Into the far, narrower end of this he inserted
a plug of soft wood, attached to which, and carried through the
quill, was a long thread, by which the plug could be withdrawn.
Having performed tracheotomy on a dog (and he recommends
that the animal should be fasting) he opened the abdomen, liga-
tured the duodenum below the pylorus, and below the entrance of
the bile and pancreatic ducts, laid open the duodenum, sponged
the interior carefully, and then introduced the quill into the
mouth of the duct. The near, broader end of the quill was by
means of rolls of paper smeared with paste, firmly fitted into
the neck of a small flask, in the body of which was an orifice
made on purpose to allow air to escape, and through which the
thread attached to the plug of the quill was drawn. By the
help of rings round the neck of the flask it and the quill were
securely fastened in their place, and the wound in the abdomen,
from which the flask hung down, carefully sewn up. By means
of the thread the plug in the quill was then withdrawn and in
a short time the juice was observed to drop into the flask. In
this way De Graaf succeeded jn obtaining from two drachms to
half an ounce, and in one case, that of a large dog, a whole ounce
of juice, in some seven or eight hours.

This first cannalisation of the pancreatic duct seems to have
been adopted as a temporary measure only; there is no state-
ment of the animal having been kept alive for any length of
time. By the same method De Graaf also obtained saliva from
the parotid duct, and bile from the bile duct. He collected
parotid saliva and pancreatic juice from the same animal at the

vi] Sylvius and his Pupils. 155

same time, and observed that the two juices differed in their
characters. It is interesting to note that this experiment
on the pancreas was never so far as is known repeated by
anyone until Claude Bernard in modem times took it up
again.

De Graafs record of the examination of the qualities or
characters of the juice is very meagre. There is no account of
any distinct chemical examination, he chiefly tested it by the
sense of taste. And he states that thus tested its qualities
were found to vary ; it was sometimes insipid, at other times
acid or rough, often salt, but most frequently acid-salt.

He records that he had an opportunity once of examining
the pancreatic juice of a sailor who had died quite suddenly,
and that he found the human juice identical in its properties
with that of the dog.

De Graaf then goes on to discuss the uses of this pancreatic
juice in digestion, and what he says may be taken as part of
the general teaching of Sylvius concerning digestion.

Van Helmont, knowing nothing of either salivary or pan-
creatic ducts, held, as we have seen, that digestion consists
wholly in the two actions of the acid ferment of the stomach and
of the ferment of the bile. Sylvius on the contrary (naturally
perhaps inclined to give too much weight to a new discovery)
was led to attach the greatest possible importance to saliva;
he regarded it as the type of fermentative juices, of what he
calls a mild character, and attributed much of the changes
taking place in the stomach to the saliva swallowed with the
food rather than to the ferment provided by the stomach itself.
He appears to have considered that the mucus (pituita as it
was called) clinging to the interior of the intestine was in
reality the remains of the swallowed saliva ; and he went so far
as to hint that the change which the blood undergoes in the
lungs may be due to a mingling of the venous blood of the
pulmonary artery with some fluid secreted by the trachea and
bronchi, or with the saliva which somehow or other found its
way to the lungs.

It was saliva then, in Sylvius's opinion, which was the chief
agent in bringing about the first stage of the fermentation

156 Sylvius and his Pupils. [lect.

called chylification. The second stage, according to him, is
due to interaction of the bile and pancreatic juice. We have
seen that De Graaf tried to persuade himself, by taste chiefly,
that the pancreatic juice was acid, and indeed the acidity of the
pancreatic juice was a foundation-stone of Sylvius's views on
digestion. Although, as we have seen, his chemical inquiries
were chiefly concerned with acids, alkalis and bases, and he was
above all other men of his time qualified to speak about such
things, although he might have been expected to be one of the
first to recognize that pancreatic juice was alkaline, he never-
theless, led away apparently by preconceived theory, always
insisted that it was acid. Its use in digestion was, he said, and
De Graaf repeated it, to effervesce, to ferment, with the bile.
Sylvius says,

"It is impossible that the juice of the pancreas in some
"degree or mode so acid should be mixed with the bile,
"abounding as this does in bitter and volatile salt, without
"exciting an effervescence, as may be proved by endless ex-
"amples seen in chemistry and elsewhere."

So also De Graaf: "That effervescence is excited by the
" mixture of pancreatic juice which abounds in acidity, with bile
" which abounds in volatile and fixed salt, we dare all the more
"boldly assert, since hitherto we have met with no example
" of an acid spirit meeting with a lixivious salt (i.e. a soluble salt
"derived by washing ashes) without a manifest effervescence
"resulting, provided impediments are removed."

De Graaf recognized the diflSculty presented by the fact that
when bile and pancreatic juice are mixed together out of the
body they do not effervesce ; but he overcomes this by arguing
that in this as in so many other cases a suitable temperature
is needed. " However it be, no one ought to wonder that we
"cannot demonstrate an effervescence between bile and pan-
" creatic juice when these are mixed together outside the living
" body, since neither artificial heat nor the natural warmth of
" the hand can excite such a heat as we know exists in the
"small intestine on account of the surroundings of the very
"warm viscera."

He also notices the objection that the dilution of the mixed

vi] Sylvius and his Pupils. 157

juices with the chyle would interfere with the effervescence;
but he argues that dilution may favour effervescence. "We
" answer," says he, " that oil of vitriol mixed with water excites
" a far more violent effervescence with iron filings than when it
" is used pure without any water." So completely did Sylvius
and his school identify physiological fermentation with chemical
effervescence.

Confident as Sylvius and his pupil were of the occurrence
and of the importance of this effervescence of pancreatic juice
and bile, they were far from clear as to how it promoted
digestion. De Graaf gives two uses. The efiervescence in the
first place attenuates the viscid mucus lining the interior of the
intestine, the presence of which might hinder the absorption of
chyle by the lacteals ; and in the second place it assists the due
separation of the useful parts of the food from the useless. But
he does not explain how it does this. It is interesting to note
that he attributes the white colour observable in the duodenum
beyond the entrance of the pancreatic duct to the pancreatic
juice. "As regards," says he, " the whitish colour observable in
"the more fluid parts of the food, we think that is due to
" the acidity of the pancreatic juice, for we have observed that
" many other things abounding in lixivious (soluble) salt and oil
" whiten upon the addition of acids." Here again we see how
completely the school of Sylvius identified physiological changes
with changes of a purely chemical nature.

In the time of Sylvius men's minds were full of the discovery
of the lacteals, the thoracic duct and the lymphatics, and
Sylvius had no manner of doubt that all the chyle, that is to
say, all the nutritious parts of the food, passed into the lacteals
and were so discharged into the venous system through the
thoracic duct. The blood carried to the right heart by the
upper great veins was in his view chylous blood. In the right
side of the heart it met with the blood of the vena cava, and
this Sylvius speaks of as bilious blood. Following the idea
which van Helmont seems to have held that bile is secreted by
the gall-bladder, Sylvius warmly espoused a view which had
been recently put forward, that that part of the bile which was
not needed for digestion was carried back to the liver, where

158 Sylvius and his Pupils. [lect.

it passed into the venous system and whence mixed with the
blood it was carried by the vena cava to the heart. This
erroneous view (a retrograde step from the position taken up
by Vesalius) was disproved by Glisson, and later on, as we
have seen, more distinctly by Malpighi ; but Sylvius long clung
to it. It fitted into his general theory. "Chyle," he says,
"assumes the form of blood (a superficial initial change)
"owing to the bilious blood ascending to the heart meeting
"in the right auricle and especially in the right ventricle
"with the lymphatic blood (of the superior vena cava) with
" which the chyle is mixed, and so on account of the diflFerent
" or rather opposite disposition of each (kind of blood) in certain
" of their parts provoking an eflfervescence of great moment."
This is the initial change on the right side of the heart;
but "the chyle reaches (not the superficial form only, but)
" the ultimate perfection of blood through the continued and
"tempered eflfervescence, presently to be described, which by
" reason of the breathing of air takes place in the lungs, in the
" left auricle and ventricle of the heart, and in the large trunks
" of the aorta. By the energy and help of this eflfervescence we
"think that there bursts out and springs forth the vital fire
" (ignis vitalis), which by rarefying the more fatty and oily parts,
" not only of the chyle added to the blood, but of the blood
"itself, and by loosely uniting together at the same time all
"other parts, reduces the whole into a heterogeneous, homo-
"geneous mass, and so converts the chyle into true blood."

All this is wordy and vague enough ; nor is he at all more
distinct when he dwells on that breathing of air which, as he
has just said, brings about the above changes. After giving a
fair description of the mechanics of respiration he goes on to
say,

" By what power, however, or in what manner and way the
" inspired air so alters the blood is not equally clear. I, for my
" part, think that it is brought about by reason of there being
"dispersed in the air nitrous and subacid particles able to
"condense the rarefied and boiling blood and so to gently
"restrain its ebullition."

Wordy and vague as his exposition is, we cannot however

vi] Sylvius and Ms Pupils. 159

fail to recognize the efforts of a man working on van Helmont's
lines, but attempting to shew that the fuller knowledge of
chemical change which he had gained by studying the actions
and reactions of various liquids and salts, which now dissolving,
now precipitating each other, now provoking, now checking
ebullition or effervescence, that is to say the development of
gas, pointed to the conclusion that it was unnecessary to take
refuge in subtle influences and occult agencies, but that all
the changes in the body were but larger and more complex
examples of the changes which could be produced in the
laboratory.

This is pointedly shewn by what Sylvius taught concerning
the secretion of urine. I have already referred to Borelli's
mechanical theory of renal secretion. Sylvius is not content
with this. He says:

" Although one may reasonably suspect that the material of
" the urine undergoes some special change while it is being
" strained through the papillae of the kidneys, it seems to me
"exceedingly probable at least that the blood and even the
"chyle is in the heart itself, through the vital effervescence
" which it there undergoes, prepared for the secretion of the
" urinary serosity, and that it is the completion only of the
" secretion which takes place in the kidneys." And then follow
these remarkable words. "Although I cannot as yet fully
" follow out the process, nevertheless I hope to arrive at it by
" the process of precipitation."

Reading between the lines by the help of the knowledge
which we have gained since those days, we may find in Sylvius's
words a prophecy of that limitation, in which we now believe,
of the work of the kidney to the task of secreting, by mere
elimination, the urea already formed in the tissues and carried
to the kidney by the blood. But I quote the words also to
shew how complete was Sylvius's confidence in his chemical
methods. The change in the blood preparatory to the actual
work of the kidney itself, was, he had no doubt, a mere
chemical process, such as he might imitate in his laboratory,
adding one clear liquid to another, and observing how a
cloud of solid particles made its appearance, particles which

160 Sylvius and his Pupils, [lect.

might be strained off by a sieve such as the kidney seemed
to be.

Borelli, as we have seen, while accepting the old view of
animal spirits residing in the brain and nerves, framed a
physical mechanical conception of them ; in his eyes the animal
spirits became a fluid of peculiar physical features, but still a
corporeal fluid, acting in a mechanical way. Sylvius also accepts
the animal spirits, but to him they become a chemical fluid, a
fluid with chemical properties, a fluid of the type of common
alcohol, existing, flowing in a pure state perhaps in the nerves,
but capable of mixing elsewhere with the blood. This is seen
in his view of the spleen :

"Since the spleen serves neither for sensation nor mere
" movement, it must be for some other purpose that it receives
" in such notable quantities the animal spirits (as indicated by
"its great nerve supply). For what end can it receive these
" except that they may enter into and be intimately mixed with
" the inflowing (arterial) blood, and make that blood more subtle
"and spirituous than its wont, that is to say, more complete
" than the rest of the (arterial) blood which is already perfect,
" in other words, more than perfect ?"

These two men, Borelli and Sylvius, stand out in the middle
of the seventeenth century as the founders of two distinct, and
indeed contending schools of thought. Borelli sought to explain
most, if not all the phenomena of the living body as mere
problems of the new mathematical, mechanical, physical science,
and so became the founder of the iatro-mathematical school.
Sylvius sought to explain the same phenomena as mere
problems of the newborn chemical science, and so became the
founder of the iatro-chemical school. But the two were men
of a very different mould.

Borelli had a foundation of exact, definite, proved know-
ledge to build upon; his mind was a strong and acute one;
he himself rarely, if ever went further than facts and his
reason led him, save perhaps when he, as all his school are
tempted to do, trusted too much to the power of a formula
to carry him over gaps where a knowledge of facts was
wanting. He would have been the first to scoff at the handi-

vi] Sylvius and his Pupils. 161

work of some coming after him who called themselves his
disciples.

Sylvius had no such exact knowledge at his back. He was
groping his way in the dim twilight of a rising but not yet
risen science; in that dim light he confounded shadows with
things, and mistook the size of images looming in the mist of
the dawn.

Moreover, he had neither the strength nor the width of
mind of Borelli. He was one of those who think that a
well-sounding phrase is of necessity a carrier of truth, and
he was also one of those who are prepared to explain every-
thing, and are satisfied themselves with every explanation
which they give. For almost every physiological problem he
had a chemical illustration ready at hand; and he seems to
have had no manner of doubt that an adequate knowledge of
alkalis and acids would carry him triumphantly through all the
difficulties both of health and disease. While Borelli was in
the main a philosopher only, Sylvius was an active physician ;
as he considered health to be ordered and appropriate chemical
change, so he regarded disease to be excessive or deficient or
perverted chemical change, a change which he hoped to cure by
the skilful addition or withdrawal of acids and the like. And
though his followers abused chemical, as much as Borelli's
followers abused physical knowledge, none of them perhaps
ever exceeded their master in the unbounded confidence which
he had in the validity of his method.

The importance of Sylvius in the history of physiology
attaches as we have seen rather to his zealous teaching of the
value of chemical knowledge as a means of solving vital pro-
blems, than to any special discoveries of his own. He was
happier when dealing with digestion than with other pheno-
mena, though his success in this he owed largely to Stensen
and De Graaf And one cannot but admit that in attaching
such great importance as he did to the pancreatic juice, wrong
as his interpretation of the nature of the action of that juice
might have been, he anticipated by some two centuries the
labours of Claude Bernard. But even that merit soon seemed
to be taken away from him.

F. L. 11

162 Sylvius and his Pupils. [lect.

In the year 1653, just as Sylvius was rising into note, there
was bom at SchaflFhausen in Switzerland one Jean Conrad
Peyer, who studying at Basel and Paris, practised in his native
town, dying there in 1712.

In 1677, five years after Sylvius's death, Peyer published a
little tract, Exercitatio anatomica medica de glatidulis intestino-
runiy in which he described certain new glands, scattered over
the intestine, which he says he had discovered in 1673. In
this work he gives a very careful account of the bodies ever
since known by his name, indicating their position on the free
border of the intestine, and their increased abundance in the
lower part of the small intestine, in the ileum, and distin-
guishing between the single solitary glands and the patches
of agminated glands. He describes them however as being
provided, each, with a minute pore opening into the interior
of the intestine, through which when the gland is pressed a
pale fluid exudes. He discusses at some length whether the
new glands are conglomerate (secretory) in nature, or conglo-
bate (lymphatic), and decides in favour of the former view on
the grounds that each gland possesses a duct, and is well
supplied with arteries, whereas no lacteals or lymphatics seem
to proceed from it, and indeed the lacteals arise from the
attached border of the intestine, whereas the glands in
question are found on the free border.

He argues that the secretion from these glands must play
an important part in the digestion of food, and suggests that
they are more abundant in the lower part of the intestine
because as the food descends from the duodenum the eflBcacy
of the pancreatic juice must become more and more exhausted.

This discovery by Peyer fitted in very well with another
discovery made a few years later by another Jean Conrad.
Jean Conrad von Brunner, bom at Dieflfenhofen in 1653,
the same year as Peyer, after studying and graduating at
Strassburg, and travelling in Holland, France, and England,
was in 1687 called to the chair of Medicine in Heidelberg.
He afterwards became Court physician at Dusseldorf, and
having had great success in practice died at Mannheim in
1727.

vi] Sylvius and his Pupils. 163

In 1682, five years before his call to Heidelberg, he pub-
lished a little work, Experinienta nova circa pancreas, embody-
ing the results of work which he had begun ten years before.

In this he made known that he had succeeded several times
in removing from a dog nearly the whole of the pancreas, and
in keeping the animal alive afterwards for a considerable time.
He removed nearly, but not quite, the whole of the gland ; the
extreme end lay so deep in the body that it could not be
reached by the knife.

He insisted that the animal when it recovered from the
effects of the operation, as in most cases it did, in no way
sufiered in health. It ate, drank, ran about as usual, was
well nourished, and all its digestive functions were carried on
normally. Obviously says Brunner, Sylvius and De Graaf were
wholly wrong in attributing the importance which they did to
the digestive powers of the pancreatic juice. The animals on
which I operated secreted no pancreatic juice into the intes-
tine, the duct and nearly the whole gland having been done
away with ; yet they digested as usual.

Upon entering into the professorial chair at Heidelberg, in
1687, Brunner published a Dissertatio inauguralis de glandvlis
duodeniy in which he described the glands since known by his
name. He states that these glands yield a fluid like pancreatic
juice, and he speaks of them as being a ' pancreas secundarium/
He had mentioned his results of extirpation of the pancreas to
his friend Peyer before the latter wrote the tract just men-
tioned ; and Peyer saw in Brunner's experiments a confirmation
of his view that the glands described by him carried out an
important part of intestinal digestion. Brunner himself how-
ever was inclined to think that Peyer's glands only secreted
a mere mucosity, and that the really active agent in intestinal
digestion was to be found in Brunner*s glands.

In view of the connection between extirpation of the
pancreas and glycosuria made known by modem researches it
may be interesting to note that in an experiment in which
Brunner had first removed the spleen, and on recovery from
that operation the pancreas also, " it was especially to be seen
" that the animal made water very frequently, and that he was

11—2

164 Sylvivs and his Pupils. [lect.

" very thirsty, drinking largely of water in proportion to the
"discharge of urine." But as Brunner observes, the acute
Malpighi has noticed a similar result after ligature of the
vessels of the spleen only. These are Malpighi's words :

" In a dog of as yet tender years a wound was made in the
" left hypochondrium, and the blood vessels of the protruding
"spleen and attached omentum were ligatured with a thread
" close to the hilus of the spleen ; everything was presently re-
" placed in its former position, the peritoneum and the muscles
" were sutured and the skin loosely united. After the lapse of a
" few days the wound had healed. After some weeks the animal
" was strong enough to perform with enjoyment all its proper
'* functions ; so long as it lived no trace of any interference with
" health could be observed. Having become more hungry than
" before, it took its meals eagerly, devouring bones and food of
"all kinds. One thing only I observed, namely that it made
"water abundantly and most frequently, in fact continually.
"Though all dogs are continually doing this, it seemed in
" this respect to outdo all its fellows. Its habit of body was
"in every respect sound; indeed it became fat, and in other
"respects, in quickness and alacrity it equalled its fellows."

Post-mortem examination shewed an atrophy of the spleen,
but hardly any other abnormality.

In another experiment, in which the pancreas alone was
removed, Brunner observes : " I had bought the animal from a
" butcher, and after the operation it also was hungry. It was
" continually going to its old master s shop and stealing pieces
" of meat. Indeed it carried on this game to such an extent
" that the butcher came to me and demanded that it should be
" killed. This however I put oflf doing since I wanted to enjoy
"for some time longer such a pleasant experience as the
"animal's condition afforded me." In another experiment too
the animal was particularly hungry and greedy; but in this
case it is especially noted that there was no other symptom,
"he was not more thirsty than before the operation."

With Brunner and Beyer's discovery, the short-lived glory
of the pancreatic juice, raised up for it by Sylvius and De Graaf,
passed away. The minds of physiologists went back to the

vi] Sylvivs and his Pupils. 165

older view that the stomach was the chief seat of digestion, and
that bile either served in some way as an aid to gastric digestion,
or was merely an excrement.

Concerning gastric digestion itself, two views contended for
prominence. Borelli, with his mind directed chiefly to me-
chanical effects, had pointed out the great grinding, crushing
force which was provided for by the muscular coats of the
stomach. He calls attention to the fact "that in birds with
" few exceptions the crushing, erosion and trituration of food is
" effected by the muscular stomach itself, compressing one part
" of its homy lining against another. Thus with the help of
"small hard and sharp pebbles contained in it, which serve
" instead of teeth, the stomach by pounding the food swallowed
"and rubbing its inner surfaces on it this way and that, like
" millstones, crushes the parts of the food until they are con-
" verted into a very fine powder. This at Pisa, at the bidding
" of his Serene Highness Duke Ferdinand II., I ascertained by
" experiment to be quite true. For I introduced by the mouth
" into the stomach of turkeys, glass globules, or empty vesicles,
"and leaden cubes, similarly hollowed out, pyramids of wood
" and many other things, and the next day I found the leaden
"masses crushed and eroded, the glass pulverized and the
"remaining ingesta in the same condition."

He admits however that birds of prey and fishes which are
destitute of teeth and possess not a fleshy but a membranous
stomach like that of a quadruped, digest their hard food in a
different manner. " These animals consume flesh and bones by
"means of a certain very potent ferment much in the same
" way as corrosive liquids corrode and dissolve metals. Such a
" corrosive juice is poured forth by the small glands with which
"the membranous substance of the stomach is crowded, as
" I have most clearly seen in the stomach of the Dolphin, in
"which the small glands are very stout and prominent.'*

Quantitative as he always was he desired to estimate the
exact force of these muscles of the stomach, and he proceeded
on the same plan as that which he had adopted for determining
the force of the heart systole.

" Having noticed that some filberts possess a shell so hard

166 Sylvivs and his Pupils. [lect.

" that they can hardly be broken by the molar teeth of man, I
" introduced some of these by the mouth into the stomachs of
* turkeys and observed on the following day that they were
"broken and pulverized. And because it might be supposed
" that their woody husks had been macerated and softened by
"some fermentative juice, I forthwith introduced into the
"stomachs of other turkeys glass vesicles, so stout that they
" could with diflSculty be crushed with the teeth, and I found
" these on the following day in the faeces reduced to powder.

" Hence since the action of these two organs, that is to say,
"the teeth and the fleshy stomach is similar, for they act by
" pressure like a winepress, and overcome the same resistance,
" viz. the hardness of the same glass vesicles, we may therefore
" conclude that the motive powers of the two are equal. But
" we have already shewn that the absolute force of the muscles
" which close the human jaw represents a power greater than
"that of a weight of 1350 lbs. Therefore the force of the
" turkey's stomach is not less than the power of 1350 lbs."

Borelli, as we have just seen, though he appears to think
that in most birds the digestive action is wholly mechanical,
and indeed he maintained that the pebbles in the stomach
might be not only mere mechanical aids, but when crushed
might serve for nutriment, admits in the case of some stomachs
a corrosive juice. In this point as in others the followers of
Borelli went beyond their master, and the iatro-physical school
after him were prepared to deny chemical action in all cases,
and to maintain that digestion was in reality a mere trituration
of the food by the muscular mill of the stomach into the creamy
mass known as chyle.

The iatro-chemical school on the one hand, following van
Helmont and Sylvius, contended that the change in the stomach
was chiefly if not wholly a chemical change effected by a
process of fermentation. Opinions differed however as to what
was the efficient agent of the process. It was generally recog-
nized that the lining membrane of the stomach was glandular
in nature ; this in many creatures, such as birds, was obvious.
But many were inclined to attach greater importance to a juice,
such as the saliva, which was poured forth by a conspicuous

vi] Sylvitts and his Pupils. 167

duct, than to a fluid which seemed Bimply to ooze from a
membranous surface ; and these were led to regard the change
in the stomach as brought about not by the independent action
of a ferment belonging, as van Helmont had thought, to the
stomach itself, but by such a ferment with the help of the
swallowed saliva, or even by the saliva itself.

After the works which I have just mentioned we have to
wait a long time, for many years, for in fact the greater part
of a century, before we come upon another solid addition to our
knowledge of the subject.

It is true that during the remainder of the seventeenth
century new truths about chemistry, new views about chemical
action were being continually gathered in. It is true that
at the close of the seventeenth and the beginning of the
eighteenth century there flourished two men who achieved
great eminence as chemists and who were assiduous in applying
their chemical knowledge to physiology; but so far at least
as digestion is concerned their influence was that rather of
expositors than of discoverers. One of these was George Ernest
Stahl, who was bom at Anspach in 1660 at the time when Sylvius
was in his fullest vigour. After studying and graduating at Jena,
he became Court physician at Weimar, and in 1694 Professor of
Medicine at Halle; but in 1716 being made physician to the
King of Prussia, he moved to Berlin, where he died in 1734 He
was an accomplished chemist, and his name must always be
borne in mind in dealing with the history of science, if for
nothing else for the reason that he was the author of the
famous theory of phlogiston, which ruled with a rod of iron, as
it were, the thoughts of natural philosophers for a hundred
years.

His general views he seems to have learnt, in the first
instance, from Wedel, his teacher at Jena, who was an ardent
spiritualist and who wrote a tract on the archaeus; but in
chemistry he sat at the feet of Johann Joachim Beccher, of whose
Physica Suhterranea, a treatise on chemistry, he published an
edition in 1703. Beccher developed at some length his views
on the essential principle of fire, but does not seem to have

168 Sylvitis and his Pupils. [lect.

used the word phlogiston. In the Specimen Beccherianum
which Sylvius appended to his edition of the Physica, and
in which he expounds Beccher's theoretical views, he says,
"Briefly, in the act of composition, as an instrument there
"intervenes and is most potent, fire, flaming, fervid, hot;
" but in the very substance of the compound there intervenes,
"as an ingredient, as it is commonly called, as a material
" principle and as a constituent part of the whole compound
" the material and principle of fire, not fire itself This I was
" the first to call phlogiston." He had used the phrase several
years before, as early as 1697 at least.

The pendulum swung far in one direction when Sylvius
threw aside all van Helmont's subtleties and spiritualistic
conceptions, his ferments which acted with a power higher than
and different from that governing ordinary chemical changes,
his archsei of which the ferments were the instruments, and
his sensitive soul of which the archsei were the servants —
threw aside I say all these and maintained that the events of
the living body were ordinary chemical events, and attempted
to explain digestion, respiration, and everything else by means
of an effervescence like that which he witnessed when vitriol
was thrown on iron filings or on long-exposed ashes. But the
pendulum swung back again in the old direction, with as great
if not greater impetus when Stahl put forward and brilliantly
maintained the view that all the chemical events of the living
body, even though they might superficially resemble, were at
the bottom wholly different from the chemical changes taking
place in the laboratory, since in the living body all chemical
changes were directly governed by the sensitive soul, anima
sensitiva, which pervaded all parts and presided over all events.

Stahrs * sensitive soul,' of which I shall have somewhat
more to say in a subsequent Lecture, was something very
different both from the sensitive soul of van Helmont and
the rational soul of Descartes. To the latter indeed it
was, in truth, in full antagonism. In Descartes' view, the
human body apart from the rational soul was a machine,
and the phenomena of man, apart from those which were the
direct expression of the activity of the rational soul, were the

vi] Sylvius and Ms Pupils. 169

phenomena of a machine governed by ordinary physical laws ;
had chemistry been as advanced in Descartes' time as in Stahl's
he might have added chemical laws. To Stahl on the contrary
a machine was exactly that which the animal body was not ;
its phenomena were not the phenomena governed by physical
and chemical laws, but phenomena obeying laws of a wholly
dififerent kind, the laws of the sensitive soul ; the sensitive soul
made itself felt in even the simplest and so to say lowest
changes of the body.

With van Helmont, Stahl had much more kinship, and
indeed his views may to a certain extent be regarded as a
development of van Helmont's ; the sensitive soul of Stahl is
that of van Helmont with two differences only. The sensitive
soul of Stahl works directly on chemical processes, without the
intervention of archsei, and is not a mortal something associated
with, and as it were the shell of an immortal mind, but it is
itself the immortal principle, spiritual and immaterial, coming
from afar, and at the death of the body returning to whence it
came.

Stahrs fundamental position is that between living things,
so long as they are alive, however simple, and non-living things,
however composite, however complex in their phenomena, there
is a great gulf fixed. The former, so long as they are alive, are
actuated by an immaterial agent, the sensitive soul, the latter
are not. This position he developes at great length in his
treatise. Be mixti et vivi corporis vera diversitate, * On the real
difference between a chemical compound and a living body.'

A living body is distinguished from a non-living merely
compound body by the fact that though capable of change and
indeed, in the very development of its activity, continually
undergoing changes, it nevertheless maintains for a given period
an identical existence.

" This very preservation of a thing essentially destructible
" by which its destruction through its own activity is prevented
" is exactly that which we ought to understand by the common
" word * vital.' This is the feature by the absence of which a
" body so far as it is simply a compound body contrasts with and
" is distinguished from a body which is living."

170 Sylvius and his Pupils. [lect.

Further, the living body is fitted for special euds and
purposes; the living body does not exist for itself; it is
constituted to be the true and continued minister of the soul.
The body is made for the soul, the soul is not made for, and is
not the product of the body.

" We may therefore rightly and truly conclude that all the
"actions of the body, both those which concern its structure
" and those which relate to the preservation of its composition,
"are carried out by the soul itself for its own uses and ends,
" and are directed and brought to completion, knowingly and
" properly, in the proportions and relations which fit those ends
" and uses."

The soul builds up the body and makes use of it for its own
ends:

"Vital activities are directly administered and exercised
"by the soul itself, and are truly organic acts carried out in
" corporeal instruments by a superior acting cause, in order to
"bring about certain effects, which are not only in general
"certain, and in particular necessary, but also in each and
"every particular adapted, in a special and yet most com-
"plete manner, to the needs of the moment and to the
" various irregularities introduced by accidental external causes.
"Vital activities, vital movements, cannot, as some recent
"crude speculations suppose, have any real likeness to such
"movements as, in an ordinary way, depend on the material
" condition of a body and take place without any direct use or
" end or aim."

Van Helmont, as we have seen, regarded archsei in the first
degree, and ferments in the second, as agents intervening
between matter, with its material properties, and the im-
material sensitive soul. Stahl ridicules the idea of there being
any need of a number of such intermediate agencies between
the soul and matter. One link between spirit and matter is
necessary, and one only : that one is * motion.'

"That which both preserves the whole body, and provides
"for and carries out the uses of the soul in the body, is a
" something which on the one hand is quite dififerent from the
"essential and proper nature of the body itself, and on the

vi] Sylvius and his Pupils. 171

*' other hand ife twin to the essential, absolute and genuine
"nature of the soul itself, — a something which is in itself
"incorporeal, just like the soul itself, but powerful and active
"in the actual body, like again the soul itself. Moreover,
"it is clear that this something ministers to the wants of
" the soul, not only so far as the existence and maintenance of
"the body is concerned, but also and especially in the naked,
" pure, and direct uses and purposes of the soul. And that in
"such a way that the soul even in its highest functions and
"in its supreme activity has such clear, true, full power over
"this something of which we are speaking, that it quite
"absolutely governs it, increases it, diminishes it, and turns
"or directs it, according to its judgment. This something
"indeed so simply and absolutely belongs to the soul, even
"in its most direct acts, that whenever anything which is
" truly and essentially belonging to n part of the soul sets out
"to become active, or to accomplish anything, it always
" discharges that duty, always accomplishes that act by means
" of this very something of which I am speaking, which thus
"serves as its true instrument; this something, however, is
"nothing else than * motion.' By motion indeed the soul
"carries out all its doings.'*

And he goes on to shew how all the phenomena of the
living body, in their threefold aspects, the phenomena con-
cerned in the preservation of the material composition of the
body, in the formation and repair of structures, and in sensation
with all its consequences, are all of them, to use the words of a
modem writer, at bottom ' modes of motion.'

Stahl applies these views to the physiology of digestion.
He admits, or seems to admit, fermentation as a property of
non-living things, and seems to regard putrefaction as a sort
of fermentation also possible in and belonging to non-living
things. He even seems to admit that the ferments of saliva
and pancreatic juice are such non-living agencies ; though he
refuses to believe in a gastric ferment. " Some people suppose
"that gastric digestion results from the action of particular
" and specific ferments, and indeed go so far as to regard the
" stomach as not only the seat but also the origin of a particular

172 Sylvivs and his Pupils. [lect,

"ferment, whereas in the whole construction of the stomach
" nothing peculiar is observed which would render the elabora-
" tion of such a special agent likely."

But even admitting the existence and action of various
ferments, the physiology of digestion is according to Stahl
still far from being explained.

"Although the medical schools, following van Helmont,
"rightly judge, as a general conclusion that the resolution
" of food takes place after the fashion of a fermentation, the
"particular way in which it occurs is involved in almost in-
" superable diflSculties. The chief of these consists in this that
" not only the fermentation of fermentable things takes place
"far more rapidly in the stomach than outside it, but also,
"things subject outside the body to no fermentation at all,
" unless it be that of putrefaction, undergo as it were a special
" kind of fermentation in the stomach, and do not follow that
" kind to which under other circumstances they are prone, but
"are overtaken and overcome by this digestive fermentation.
" Then there is the specific character which is imposed on the
" digested material as is seen in the differences which exist in
" even the crude chyle, or the milk of different animals living
" on exactly the same food.

"In any case the fermentation which takes place in the
"alimentary canal is not an ordinary fermentation such as
"occurs in a merely compound not-living body, but a most
"special character is impressed on the change, impressed by
"the energy of the soul."

Stahl's teaching, in fact, was briefly this :

Learn as much as you can of chemical and physical pro-
cesses, and in so far as the phenomena of the living body
exactly resemble chemical and physical events occurring in
non-living bodies, you may explain them by chemical and
physical laws. But do not conclude that that which you see
taking place in a non-living body, will take place in a living
body, for the chemical and physical phenomena of the latter are
modified by the soul. The events of the body may be rough
hewn by chemical and physical forces, but the soul will shape
them to its own ends, and will do that by its instrument, motion.

vi] Sylvius and Ms Pupils. 173

He thus stands forth at the close of the seventeenth century
as the founder of 'animism/ which doctrine, though his sensitive
soul fell back later to the lower stage of *a vital principle/
maintained itself in many minds through the two succeeding
centuries, and exists at the present day.

The other man, a man of a wholly different mind, was
Hermann Boerhaave; but of him it will be best to speak in
connection with his even more illustrious pupil Albert von
Haller, and in this aspect he belongs wholly to the eighteenth
century.

LECTUKE VII.

THE ENGLISH SCHOOL OF THE SEVENTEENTH
CENTURY. THE PHYSIOLOGY OF RESPIRATION.

While we have been following the gradual enlightenment
of the physiological world we have seen how the spot of light
which was the centre of illumination shifted from place to
place, and shone now in one University, now in another. We
have seen it bursting out brilliantly at Padua in Vesalius, less
brightly in Fabricius; it appeared meteor-like in Switzerland
in Paracelsus ; then it moved to London and shone in Harvey.
Anon it burst out in the Northern countries in van Helmont
at Brussels, in Stensen at Copenhagen. It flitted back to
Italy, to Borelli in Pisa, to Malpighi in Bologna, and once more
returned to the North to Sylvius in Leyden and to others.

I have now to ask you to go back with me once more to
London. Englishmen are justly proud of Harvey, and they
take some credit for Glisson. They may also boast of a little
band, worthy successors of Harvey, who in the middle and latter
part of the seventeenth century made remarkable progress
in the knowledge of the true nature of breathing.

The exact physical science which Galileo had begun at
Pisa soon crossed the seas and passed to England, stirring
up a knot of men to pursue studies of the same kind, a knot
of men who some few years afterwards founded the Royal
Society of London, for the advancement of natural knowledge,
in the hope, a hope not wholly unfulfilled, that it would help
them in their "attempts by actual experiments to shape out
a new philosophy or to perfect the old."

LBCT. vn] The English School. 175

Conspicuous among these was a gentleman of leisure, of
noble birth, the Honourable Robert Boyle, whose keen intellect
pierced far into every problem to which he turned his mind,
and who touched nothing without leaving his mark upon it.

It would be out of place for me here to attempt to give
even a sketch of Boyle's influence on the progress of physical
and chemical science. I must content myself with speaking
only of his notable contribution to the solution of respiratory
problems, a contribution which was part of and incidental to
his researches on the general properties of the atmosphere.

Before doing so I must briefly recall to your minds the
progress which had been made in the knowledge of this subject
of respiration up to the time when Boyle made his notable
experiment.

In the old Galenic doctrine the movements of respiration,
as we have seen in speaking of Fabricius, served a double, or
rather a triple purpose. In the first place the air introduced
by breathing served to regulate, to maintain, and at the same
time to temper, to refrigerate the innate heat of the heart,
that fire which, placed in the heart at the beginning, continued
there all life long and was the one source of the warmth of
the body. In the second place the pumping action of the
chest served to introduce into the blood the air which was
necessary for the generation in the left side of the heart of
the vital spirits, which were thence distributed over the body
by the arteries. In the third place the same action served to
get rid of the fuliginous vapours, the products of the innate
fire burning in the heart. Both the pure air engendering the
vital spirits, and the foul vapours the etfect of the heart's
labours, were supposed to pass by the vein-like artery, the
pulmonary vein, the one one way, the other the other.

The absurdity of supposing that the same channel could
serve for these two currents is put forward by Harvey in his
book as the first diflBculty which meets one in considering the
validity of the Galenic doctrines ; but it was a difliculty which
Fabricius did not feel or which at least lay lightly upon
him.

With Harvey s demonstration all this view fell crumbling

176 The English School [lect.

to the ground. It was seen that as the blood-stream swept
through the luugs from the right to the left side of the heart
a great change in the blood took place ; from being venous it
became arterial. But what the change exactly was, or how it
took place, and what the connection was between the change
in the bl<iod and the movements of the lungs, and indeed what
was the exact purpose of the bellows-like heaving and falling
of the chest remained unsolved problems.

Van Helmont as we have seen, if we may distinguish
between his fourth and his fifth fermentation, thought that the
blood in passing through the lungs suffered a fermentation
by which it became lighter in colour and more volatile, a
fermentation different from and introductory to that by which
the vital spirits were engendered in the left ventricle, and
across the septum in the right ventricle also. But he is not
clear on this point, and in any case he seems to have attributed
nothing to any mingling of the blood in the veins with the air
in the lungs.

When we come to Borelli we pass at once into a clear
understanding of the problem so far as the mechanical side of
it is concerned. He applied to the mechanics of breathing the
new knowledge which had been arrived at on the one hand of
muscular contraction, and on the other hand of the pressure
and elasticity of the atmosphere, and so at once reached the
truth that inspiration Consists in the entrance of air by virtue
of the pressure of the atmosphere into the chest enlarged by
the muscular contraction of its walls, and expiration in the exit
of the air so entering, mainly at least by cessation of contraction.
Fabricius had, as we have seen, some sound views on this
matter, but Borelli went far beyond him.

When he came to deal with the chemical aspects of
breathing Borelli rejected instantly and peremptorily the old
view that the movements of breathing were for the cooling
and ventilation of the innate fire of the heart, or for expelling
the vapours generated by such a fire.

In discussing the subject in his book he lays down by the
help of formulae and figures certain propositions concerning the
laws of mixture of the minute particles of diverse fluids exposed

vii] of the Seventeenth Century. 177

in certain channels to certain pressures; and he finishes his
exposition with the following words:

"I have expounded the above matters because eminent
"anatomists have thought that breathing was instituted in
"order that the chief parts of the blood (namely the serous,
"and coloured parts as well as the chylous material together
"with the lymph) may be completely mixed in the lungs so
" that for instance the minutest particles of the one may come
" in contact with and receive among themselves the minutest
" particles of the rest. And they think that this is effected by
" the repeated rythmic pressure exerted by the inflated vessels^
"Therefore after my wont, without mentioning any names, I
"will, in the interests of truth, expound the reasons which
"render such an opinion doubtful." And this he goes on
to do.

Now Malpighi, in the letter to Borelli in which he an-
nounced his discovery of the true structure of the lung, and
which Borelli at the time loaded with praise, had ventured
to put forward just such an explanation as that given above
of the use of the lungs. It is his old friend Malpighi whom
Borelli is here attacking.

And Malpighi, in his autobiography finished just before his
death, and published by the Royal Society in 1697 as part of
his posthumous works, in describing how his little tracts were
received by the learned world, refers to the matter in the
following way:

"You will wonder, Reader, when I tell you that the most
" learned Giovanni Alphonso Borelli whom I a little while back
" spoke of as most anxious that my Letters should be published,
" now breaks out into opposition to and severe criticism of my
"views. The reason which has led him to do this is because
** the literary intercourse which existed between us having been
" broken off he became so inflamed with anger against me and
" mine that in the book which he composed in his last declining
" years, namely the one on the movement of animals, he seized
" the opportunity of disproving my opinions. In this book, he,
"without mentioning my name attacks with many arguments
"the use assigned by me to the lungs." He then in turn
p. L. 12

178 The English School [lect.

refutes Borelli s arguments ; apparently he remained by his old
opinion until his death.

Borelli sums up his exposition of the erroneous views put
forward concerning the purpose of breathing as follows :

''It is clear from what has been said that the use of
" breathing is not the cooling of the excessive heat of the heart,
" nor the ventilation of the vital flame, nor the mixture of the
"heterogeneous parts of the blood brought about by the
" pressure of the inflated vesicles of the lungs, nor merely the
" passage of blood from the right to the left ventricle of the
" heart in order that the circulation may be carried on. But so
"great a machinery of vessels and organs of the lungs must
" have been instituted for some grand purpose ; and that we
" will try to expound, if possible, though we shall stammer as
"we go along."

He remarks that, in spite of the experiment that air blown
through a tube into the bronchial tubes does not enter the
pulmonary vein, many authors maintain, and justly maintain,
that air does somehow find its way from the lungs into the
blood. These authors suppose for this purpose the existence of
minute pores leading from the interior of the lungs into the
blood vessels. Such a supposition, however, is, in his opinion,
not necessary, since air dissolved in liquids can pass through
membranes, and there is always in the bronchial passages some
fluid in which the air might be dissolved.

He goes on to insist that "air taken in by breathing is
the chief cause of the life of animals," far more essential than
the working of the heart and the circulation of the blood.
A frog will live after its heart has been wholly cut away, and
insects may be divided into pieces and yet live for a while.
The stoppage of breathing, on the other hand, brings about in
all cases the cessation of life.

"The experiment which proves most completely the truth
" of the assertion (that air is necessary to life) is the sudden
" removal of air by Boyle's pneumatic machine, or better still
"by the Torricellian vacuum with the help of mercury.
" Animals of all kinds shut up in such a vacuum immediately
"fall down dead; but if the air be instantly renewed with
"care, may be brought to life again."

vii] of the Seventeenth Century. 179

He recognised that particles of the air taken into the lungs
enter in and become mixed with the blood. But true to his
position as a physicist dealing only with problems capable of
being solved with mathematical certitude, and refusing to
attempt to solve problems in any other way, he rejects all
vague chemical suggestions as to particular chemical substances
being drawn from the air and mixed with the blood. "The
"particles of the air mixed with the blood do not increase its
" flexibility, nor do they produce an effervescence in the heart
" by reason of their elastic force or of their nitrous nature." He
invents a physical hypothesis of molecular movement. He sup-
poses that the entrance of air into the blood produces continual
delicate oscillations (continuce motionis tremulce), which like
the pendulum of a clock regulate all animal actions.

This exposition by Borelli appeared in print when his book
was published in 1680-1 ; .but, as we have already said, much
which is to be found in the book had been publicly taught by
him many years before, while he was at Pisa. Since, as he
himself admits, he rarely quoted authorities, it is difficult in
many cases to decide whether the view which Borelli is ex-
pounding is really his own, reached by him at an early date or
has been taken from some other author who had put it forth
before Borelli s book was finished for the press. And, as we
have seen, he never really finished the book; he continued
labouring to improve it until almost the day of his death. We
may however conclude from the quotations just given that he
was acquainted with the views put forward during his life-time
by the English School of which I am about to speak ; and we
may also conclude that he rejected those views. To these we
must now turn.

Robert Boyle as all know busied himself with the new views
as to the weight and pressure of air introduced by the observa-
tions of Galileo, Torricelli, and Pascal, by which the old plenum
doctrine of Descartes was overthrown. With his new pneu-
matical engine, or air-pump (which von Guericke had just
before introduced) he made many researches on the spring or
elater of air.

He shewed in 1660 that even in a partial vacuum

12—2

180 The English School [lect.

brought about by his air-pump, and much sooner in a more
complete one, flame was extinguished and life soon came to an
end ; the candle went out and the mouse or the sparrow died.

This experiment, which is referred to in the quotation from
Borelli given above, must be regarded as the fundamental ex-
periment in the physiology of respiration. It shewed not only
that the thing called air, and not merely the movement of the
chest in breathing, was essential to the due effect of bpeathing,
but also that the change whatever it might be which was
effected by breathing was identical with that which was going
on in the burning of a candle.

The next step was taken by Robert Hooke. This man,
of singular ingenuity, bom in 1685 and dying in 1702, held for
many years, from 1664 until his death, the office of curator of
experiments to the newly founded Jloyal Society, having been
some time previously assistant to Boyle. He was one of the
earliest and most zealous users of the newly invented micro-
scope, and in his Micrographia, published by the Royal Society
in 1667, records his numerous " Observations made on Minute
Bodies of very varied kinds by Magnifying Glasses."

As Curator to the Royal Society it was his duty to perform
experiments before the Fellows at their meetings, and these
experiments, such was the versatile ability of the Curator, were
very diverse in kind, physical, chemical, and physiological.

At their meeting of Oct. 24, 1667, he delighted the Fellows
of the Society with an experiment on artificial respiration, an
account of which is given in no. 28 of the Philosophical
Transactions, The experiment of artificial respiration had
often been done before. Vesalius tells us how he used to per-
form it, and points out how the beat of the heart and arteries
grew faint and almost ceased when the action of the bellows
was stopped, and how it revived again with great vigour so soon
as inflation was begun again. But no one had drawn from the
experiment the important conclusion which Hooke drew.

In the first place having widely opened the thorax of a dog,
he shewed that the animal could be kept alive by artificial
respiration in absence of all movements of the chest wall. This
proved, and the point had been previously doubtful, or at least

vn] of the Seventeenth Century, 181

not unreservedly accepted, that the whole of the essential
business of respiration is carried on in the lungs, that the
movements of the chest are useful only so far as they bring about
the changes, the alternate expansion and collapse of the lungs.

In the second place, and this was really the important part
of the experiment, he shewed that the animal could almost
equally well be kept alive without any movement of the lung.
He kept the lung motionless but thoroughly distended by
maintaining a powerful blast with the bellows, the air driven in
escaping continually through minute holes pricked in the lung.
This shewed that the mere movement of the lungs in breathing
which had of old been thought to be the essential factor in
respiration was an incidental and not a necessary feature of the
business. The essential feature was a supply of fresh air
adequate to keep up the resulting change in the blood. The
qualities, whatever they might be, by assuming which blood
passing through the lungs became arterial and thus fit to
nourish the body were imparted to the blood not by movement
but by the mere exposure of the blood to air, that is to fresh air.
The concussions which it had been supposed by some were given
to the column of blood by the movements of breathing, had
nothing to do with the matter, nor indeed had movement any
real share in the business. The secret of the change lay in the
mere exposure of the blood to fresh air, to air made fresh, in
natural breathing, by the bellows-like action of the chest. And
Hooke at the close of the experiment asked the pertinent
question "whether suflfering the (venous) blood to circulate
" through a vessel so that it may be openly exposed to the fresh
" air may not suffice (instead of lungs and breathing) for the life
" of the animal ? "

The next step was taken by Richard Lower. I have
already referred to this singularly able man, the henchman
of the fashionable Willis, whose false fame in large measure
rested on Lower's careful, unacknowledged work.

Bom in Cornwall in 1631, educated at Westminster School
in London and afterwards at Oxford, he stayed in the latter
city tor some years, while Willis was Professor.

In 1665 he created quite an excitement by his experiments

182 The English School [lect.

on transfusion ; through these he became for a while the talk
of the town. The inordinate hopes which were raised by this
new method were never realized ; but the fact that such experi-
ments were at that time made is a striking proof of what a
revolution had been effected in men's views as to the circula-
tion of the blood in the thirty-seven years which had passed
since Harve/s book was published. Before the doctrine of the
circulation of the blood had been established, to prolong life or
cure disease by injecting blood into a blood vessel would have
seemed the height of absurdity.

The fame of his transfusion seems to have brought Lower
from Oxford to practise in London, where especially after
Willis's death in 1676 he became very popular; but his
pronounced political attitude, he was a fervent whig, stood
in his way. his practice * fell off' and he died in anything but
prosperous circumstances in 1690.

In 1669 he published his Tractatus de corde. In this he
not only gave a much more accurate description than anyone
had given before of the structure of the heart, including the
distribution of its nerves, but he also gave an account of the
physiology of the heart, in which he completed and extended
Harvey's exposition with the help of all the new exact physics
which had come to hand since Harvey wrote his work. He
gave more accurate measurements than Harvey had published
(Harvey as we know had made many observations in addition
to those recorded in his book, observations which he promised
to publish but never did) concerning the amount of work done
by the heart, and the velocity of the flow in the arteries. He
recognized the meaning of the stout walls of the arteries and
the thin coats of the veins. He noticed that when one carotid
was ligatured the other beat more forcibly on account of the
greater amount of blood thrown into it. He produced ascites
by ligaturing the vena cava high up, and intravascular clotting
by injecting milk. He was aware that the heart would beat
for a while cut away from all its connections. In short he
obtained at that early date a rough perhaps, but true view of
most of the main facts of the circulation. As a Fellow of
the Royal Society he was of the opinion that new truths

vn] of the Seventeenth Century. 183

were to be reached mainly by way of experiment, and as a
physiologist he like Harvey sought for truth in experiments
on living animals. And his experiments led him to truth.
His exposition of the circulation though less formal than that
of his contemporary Borelli, for Borelli was teaching while Lower
was experimenting and practising, not bristling as does Borelli's
with mathematical formulae and scholastic theorems and lem-
mas, comes in many respects much nearer the truth, is much
more like a modern exposition, and may with profit be read at
the present day.

But it is not to Lower's views on the heart and circulation
that I wish now to call attention. In his work on the heart
there is included the account of experiments having results
fundamental in the history of respiration.

It was known of course of old that venous blood was dark
and arterial bright, but the change was thought to take place
in the heart, on the left side of the heart ; and this view was
maintained even after the circulation through the lungs had
been accepted (though van Helmont seems to have caught
sight of the truth that the change might take place in the
lungs). Moreover the change in colour was thought to be only
a superficial accompaniment of profound diflferences between
the blood in the arteries and the blood in the veins.

Lower's careful quantitative determinations and calculations
of the flow of blood through the heart raised as he says doubts
in his mind as to " whether there could be that great difference
" between venous and arterial blood which the vulgar think."

He suspected that the change of colour took place in the
lungs as the contents of the pulmonary artery found their way
into the pulmonary veins, and that it was due simply to the
exposure of the blood to the air in the lungs. But so long as
he made observations on natural breathing he failed to satisfy
himself of the correctness of his supposition.

Hooke's experiment on artificial respiration gave him the
opportunity he desired. Examining the lungs of an animal kept
alive by artificial respiration after the chest had been opened,
he had no difficulty in ascertaining that the blood in the pul-
monary veins long before it reached the heart was florid in

184 The English School [lect.

colour. He further saw that when the artificial respiration was
stopped, when no fresh air was driven into the lungs, when the
animal was suffocated, the blood in the pulmonary veins and in
the left side of the heart became dark and venous. He took
dark venous blood from the vena cava, and injected it artificially
through the lungs. He found that so long as insufilation of
the lungs was kept up the blood ran out by the pulmonary
veins florid in colour, but ran out dark and unchanged if no
fresh air was driven in to the lungs.

He concluded that the change in colour was due simply to
the blood being exposed in the lungs to air; and he was
confirmed in this conclusion by observing the fact that a clot
of dark venous blood soon becomes florid on the upper surface
where it is exposed to the air ; and that if the cake be turned
upside down the under dark surface also soon becomes florid.

And he at once took the next step and drew the further
conclusion that the change in colour was due not to mere
exposure alone but to the blood taking up some of the air.
Arterial blood, according to him, differs from venous in that
it contains air; as the florid arterial blood passes from the
body air escapes from it and it becomes dark and venous; as
the dark venous blood passes through the pulmonary circulation
it takes up air again and once more becomes florid and arterial.

It is this continual entrance of fresh air into the blood
which renders fresh air so necessary for the maintenance of
life. " Were it not for this we should breathe as well in the
"most filthy prison as among the most delightful pastures."
The same fresh air is as much needed for our breathing as
for the burning of a flame, " in fact where a fire burns readily,
" there can we easily breathe."

Lower speaks only of air being taken up as air, and as we
have seen Borelli had also come to the conclusion that air is
taken up by the blood in the lungs ; but he writing towards the
end of the seventies might have been acquainted with Lower s
results. Neither one nor the other alludes to the possibility
of a part of the air only being taken. It was the common
opinion of the time and one which lasted for long afterwards
that air, the air of the atmosphere, was a single substance not

vn] of the Seventeenth Century. 185

a mixture of two or more things, though it was admitted that
in the atmosphere there existed besides the air proper, or pure
air, suspended as it were in this, a number of particles of a
diflFerent and probably varied nature.

Both Lower and Borelli seem to have thought that it was
the air proper, and not any special particles in it, which passing
into the blood brought about the change of colour. Hooke, in
his Micrographia in 1667, treating of charcoal and speculating
concerning flame, propounds the view that it is due to action of
a part of the air which he calls a ' menstruum,' " a substance
" inherent in and mixt with the air, that is like, if not the very
" same with that which is fixt in Salt-peter/' But he does not
go beyond this, and does not apply the same view to breathing.

It was left for a countryman of Lower, for one belonging as
he did to the University of Oxford, to take the next step in
the physiology of respiration and to bring forward reasons for
thinking that in breathing only a part of the air, not the whole
air, not the air proper, was taken up into the blood.

John Mayow, coming like Lower of a Cornish family, was
born in London in 1643, the year before van Helmont died.
Admitted a scholar at Wadham College, Oxford, he became in
due time a Fellow of All Souls. Devoted as he was to science,
physic was not his profession; he took a degree in law "and
" became noted for his practice therein, especially in the summer
"time at Bath." Yet to judge from his works one would
have thought that the whole of his time at Oxford had been
given up to continued research. In 1668, just four years before
Sylvius's death, he published, while as yet a young man of
twenty-five years, a little work containing four tracts, (1) De
sal nitro et spiritu nitro aereOy (2) De respiratione, (3) Be re-
spiratione fcstus in utero et ovo, (4) De motu musculari et
spiritibus animalibus. He eventually migrated to London and
in 1678 was admitted a Fellow of the Royal Society. In the
following year he died in Covent Garden at the all too early
age of thirty-five, "having been married a little before not
"all together to his content."

Mayow s contribution to our knowledge of respiration was
this. He shewed that it was not the whole air which was

186 The English School [lect.

necessary for respiration, and which was used for respiration,
but a particular part only of the air ; and, as we shall see, by
this particular part, though he called it by a diflFerent name,
he meant what we now call oxygen.

The formation of nitre in heaps of decomposing animal and
vegetable matter, and the properties of nitre or saltpetre,
especially as the constituent of gunpowder, had for a long time
excited the interests of chemists. Nitre was made the pivot of
various chemical theories and ideas. " Nitre, which has made
"as much noise in philosophy as in war."

Sylvius in treating of respiration, of the mechanics of which
he gives a fair description, and concerning which he had reached
the conclusion that in breathing air passes from the lungs into
the blood and produces a notable change in it, has the following
remark. " By what power however, or in what manner or way
" the inspired air so alters the blood, is not equally clear. I
" think it is brought about by reason of there being dispersed
**in the air nitrous and sub-acid parts able to condense the
"effervescing and rarefied blood and to gently restrain its
"ebullition. I distinguish however between the sub-acid and
" the nitrous parts of the air, since the sub-acid parts are for
"the most part simple, but the nitrous on the contrary are
" compound, composed of acids if you like, though not with
" any you please, but also of oily parts and lixivious salts, as
" is clearly proved by the artificial {i.e, chemical) synthesis and
" analysis of nitre."

Whether Sylvius wrote the above as the result of his own
researches or whether he had heard of Mayow's inquiries is not
certain ; but in any case Sylvius s obscure views are very
different from what we shall see to be the definite and clear
conceptions of Mayow.

In the introduction to his tract on sal-nitrum Mayow
undertakes to prove,

" That this air which surrqunds us, and which, since by its
" tenuity it escapes the sharpness of our eyes, seems to those
" who think about it to be an empty space, is impregnated with
"a certain universal salt, of. a nitro-saline nature, that is to say
" with a vital, fiery and in the highest degree fermentative spirit."

vn] of the Seventeenth Century. 187

It is this which he calls sal-nitro-aereum or spiritus nitro-
aereus, or sometimes igneo-aereus.

Mayow was a chemist, far more of a chemist than Lower
or Hooke, perhaps even more distinctly a chemist than Boyle ;
he had doubtless read carefully the works of Sylvius and
van Helmont, and had probably repeated many of their ex-
periments. He uses the current terms of the chemists of the
period; and in reference to this it may be well to note that
the word 'salt' had not yet acquired the limited meaning
afterwards attached to it; it was still often used to denote
any substance (whether elementary, as we should now say,
or compound) not distinctly metallic, or distinctly liquid.

Mayow first expounds the nature of nitre. The common
method at that time of preparing nitre was to allow heaps of
vegetable matter to decompose with exposure to the air, and
then to dissolve out and crystallize the potash nitre so formed.
He says that it is derived partly from the air and partly from
the earth. There is the sal fixum or sal alkali, or as we now
say, potash; this distinctly comes from the earth. Besides
this there is the spiritus addus, or as we now say, nitric acid.

For a while he thought that the whole of this spiritus
acidus was derived from the air, that it existed distributed
throughout the atmosphere divided into extremely minute
particles. But this seemed incompatible with the well-known
fact that the spiritus acidus is a corrosive liquid, extinguishing
flame and destructive to life. He concludes therefore that part
only of the acid exists in the atmosphere, and that part is his
sal-nitro-aereum or spiritus nitro-aereus.

In attempting to lay hold of the nature of this nitro-aereal
agent he first reminds his readers that a certain part of the
air is necessary for the maintenance of combustion. He says :

"In the first place it must, I take it, be granted that
''something in the air, whatever it be, is necessary for the
"burning of every flame. This Boyle's experiments have
"placed beyond doubt. For these shew that a lighted candle
"goes out much more quickly in a glass flask empty of air
"than in the same vessel full of air, a clear proof that the
"flame, enclosed in the flask, goes out not because it if

188 The English School [lect.

"suflFocated by its own smoke, as some have thought, but
" because it is deprived of its aereal sustenance or food
** (pabulum). For since there is more room for the reception
" of the smoke in the flask, when it is exhausted of air than
"when it is full of air, the candle ought to go out more
" quickly in the latter than in the former, if its going out was
** merely due to the smoke.

" Moreover sulphureous (i.e. combustible, he uses the time-
" honoured Valentinian nomenclature of the different natures
"of things) matter, of whatever kind, when placed in a flask
" exhausted of air, cannot be ignited either by burning char-
"coal or red-hot iron, or by the sun's rays concentrated by
" means of a burning-glass. So that there cannot be now the
" slightest doubt but that certain aereal particles are altogether
" necessary for the lighting of tire ; and indeed our opinion is
" that these same particles play the chief part in igniting fire,
" and that the form of flame depends mainly on these particles
" being agitated in a most destructive manner, as I shall shew
"more fully later on.

" But it must not be thought that the igneo-aereal food (of
" flame) is air itself; it is only a more active and subtle part
" of it. For a candle enclosed in a flask goes out although
" there is still contained in the flask an ample abundance of air.
" Now we cannot suppose that the particles of air which existed
" in the flask were destroyed by the burning of the candle or
" that they escaped and got away, for such particles are unable
" to pass through the glass. Moreover it is not probable that
" those igneo-aereal particles are a sort of perfected nitre, as
" the common opinion runs, for as has been shewn above it is
" not the very whole of the nitre but only a certain part of it
" which is derived from the air."

He then goes on to shew that the particles of air, forming
the more active and subtle part of air which is thus necessary
for combustion, exist in nitre and indeed constitute its " more
active and fiery part." For sulphur when mixed with nitre will
burn in the absence of air, in a vacuum for instance, or under
water. " Thus a squib made of gunpowder of which nitre is an
" important constituent will burn right away under water."

vn] of the Seventeenth Century. 189

For every combustion there is needed on the one hand
sulphureous (combustible) material, and on the other hand
igneo-aereal particles. Now there are no sulphureous par-
ticles in nitre, hence nitre will not burn by itself. But nitre
as just stated when mixed with sulphureous particles burns
most readily, even without the access of air.

He concludes that the aereal part of nitre is nothing else
than the igneo-aereal particles of which he has been speaking
as essential to combustion ; these particles exist, not in the sal
alkali part of the nitre, but in the spiritus acidus part ; and he
enters into an explanation why the whole nitre, spiritus acid
and sal alkali together, is better suited for burning than the
spiritus acidus itself, though this really contains the elements
essential to combustion.

It is obvious from the above that Mayow, by his nitro-aereal
or igneo-aereal salt or spirit meant nothing less than that which
we for a hundred years or more have been calling oxygen. And
he thus, with clear insight, sums up the conditions necessary for
combustion to take place :

" Concerning fire (combustion) it must be noted that for the
"ignition of this it is necessary that igneo-aereal particles
" should either preexist in the thing to be burnt or should be
"supplied from the air. Gunpowder is very easily burnt by
"itself by reason of the igneo-aereal particles existing in it.
" Vegetables are burnt partly by means of the igneo-aereal
" particles existing in them, partly by help of those brought to
" them from the air. Purified sulphureous matter on the con-
" trary can be burnt only with the help of igneo-aereal particles
" brought to it by the air."

He also recognized that in combustion the igneo-aereal
particles enter into combination with the substance burnt.
In the course of this discussion on burning he makes the
following very remarkable reflection. He was writing in 1668.
Many years afterwards in 1697 Stahl as I have said introduced
the phlogiston theory. The essence of that theory was the view
that when a combustible body, a phlogisticated body, underwent
combustion, phlogiston departed from it; the body suffered a
loss, it became de phlogisticated. The world had to wait for

190 The English School [lect.

nearly a hundred years after Stahl until Lavoisier overthrew
the theory by proving that in combustion a body suffered not
loss but gain : the metal burnt into a metallic oxide increased
in weight. This is what Mayow said more than a hundred
years before Lavoisier, many years before Stahl:

" Nor must the following point be passed over, that anti-
"monium burned by the sun*s rays (collected by a buming-
" glass) increases considerably in weight ; as may be proved by
"experiment (i.e. by actual weighing). Now we can hardly
" conceive that the increase of weight of the antimonium arises
"from anything else than from the igneo-aereal particles in-
"serted into it during the calcination."

What a zigzag path, how unlike a straight line, is man's
progress in search of truth. Here is Mayow reaching a point
far ahead, and Boyle a little later had grasped the same fact ;
Stahl drags, or seems to drag, the whole world of thought
back; and more than a hundred years afterwards Lavoisier
reaches the same point as Mayow. How true it is that the
value of a truth is not absolute ; there is a time and a place
for everything, including a new truth. If a discovery is made
before its time, it withers up barren, without progeny, as did
Mayow's.

Having thus developed his views as to the nature of com-
bustion Mayow went on to identify burning and breathing.
Both, he said, consist in the consumption of the igneo-aereal
particles of the air:

" If a small animal and a lighted candle be shut up in the
" same vessel, the entrance into which of air from without be
" prevented, you will see in a short time the candle go out ; nor
" will the animal long survive its funeral torch. Indeed I have
"found by observation that an animal shut up in a flask
" together with a candle will continue to breathe for not much
"more than half the time than it otherwise would, that is,
"without the candle.

" Nor is it to be supposed that the animal in such a case is
" suffocated by the smoke of the candle, since if the flame be
" supplied by the burning of spirits of wine no smoke is pro-
" duced (and yet the animal dies) ; moreover when a candle is

vn] of the Seventeenth Century. 191

" used the animal lives for some time after the caudle has gone
" out and its smoke has disappeared, so that we cannot suppose
"that it is suffocated by the smoke.

" The reason why the animal can live some time after the
" candle has gone out seems to be as follows. The flame of the
"candle needs for its maintenance a continuous and at the
" same time a sufficiently full and rapid stream of nitro-aereal
" particles. Whence it comes about that if the succession of
"nitro-aereal particles be interrupted, even for a moment, or
"if these are not supplied in adequate quantity, the flame
"presently sinks and goes out. Hence, so soon as the igneo-
" aereal particles begin to reach the flame scantily and slowly,
"it is soon extinguished. For animals, on the other hand, a
" lesser store of the aereal food is sufficient, and one supplied
"at intervals, so that the animal can be sustained by the
"aereal particles remaining after the candle has gone out.
** Here it may be remarked that the movements (expansions)
"of the collapsed lungs not a little help towards the sucking
"in of aereal particles which may remain in the said flask,
" and towards transferring them into the blood of the breathing
"animal. Whence it comes about that the animal does not
"perish uutil just before the aereal particles are wholly
"exhausted. And hence it is that air in which an animal
"is suflbcated is diminished in volume more than twice as
"much as that in which a candle goes out."

This latter sentence refers to another aspect of the matter.
Physicists were then much exercised and Boyle's experiments
in particular had led to much discussion about the 'spriug*
(elater) of air — the elastic force {vis elastica) of air, and the
pressure of air.

Mayow observes that when a candle is burnt in a closed
vessel over water, the water rises after the primary depression,
due to expansion from heating, has passed off; the burning
has deprived the air of some of its elastic force. He finds
by experiment that exactly the same thing takes place in
breathing. When a small animal is made to breathe in a
closed vessel standing over water the water rises. When a
mouse is put inside a cupping-glass, placed over a piece of wet

192 The English School [lbct.

bladder stretched out loosely, over the wide mouth of a bottle
for instance, the bladder bulges up into the cupping-glass.
"I have found," says he, "by experimenting with various
"animals that air (of a closed vessel in which the animal is
"allowed to remain until it dies for want of air) is by the
" breathing of animals reduced in volume by about ^fjth."

By such experiments as these "it is manifest," says he,
"that air is deprived of its elastic force by the breathing of
" animals just in the same way that it is by the burning of a
" flame. We may infer that animals and fire deprive the air of
" particles of the same kind."

Mayow as I have said, and indeed as we have seen, was
essentially a chemist, but he was also well versed in the new
physical learning of the time. It was only natural that he
should be fascinated with the elastic force which he believed to
be possessed to a peculiar degree by his igneo-aereal particles.
He attributed an exaggerated importance to this elastic force.
He enters into a long disquisition about it, and offers by means
of it an explanation of the explosive force of gunpowder. As
we have already hinted and as we shall later on clearly see the
chemical meaning of Mayow's discoveries was soon forgotten.
His chemical exposition was premature. But his physical
exposition fell on congenial soil. His igneo-aereal particles
continued to be spoken of after him, not with the chemical
properties which he attributed to them, but with the physical
properties only, simply as the elastic particles of air.

Mayow however was not merely a chemist or a physicist, he
was above all things a physiologist. In his third tract, 'On
Respiration,' he gives in the first place an exposition of the
mechanics of breathing, an exposition clearer and better, more
exact and more true than that of Borelli, free from Borelli's
pedantic formalities, an exposition which might almost find its
place in a text-book of the present day.

He explains that air enters the lungs during breathing
simply and solely because the pressure of the atmosphere or
the elastic force of the atmosphere drives air in to fill up the
increased space afforded by the enlarged and dilated thorax.
And he points out how the structure of the lung, as made

vn] of the Seventeenth Century, 193

clear by Malpighi (seven years before he was writing), is admir-
ably fitted by its vesicles and tubes for such a purpose. He
illustrates his meaning by the well-known experiment of a
collapsed bladder expanding in a closed vessel as the air is
exhausted ; and makes a quaint model of the chest and lungs
by means of a bladder inserted in the cavity of a pair of
bellows so that the mouth of the bladder is continuous with
the nozzle of the bellows. When the bellows are expanded air
rushes into the bladder and fills it, when the bellows are
brought down the air is driven out again from the bladder.

Asking the question how the chest is enlarged during
inspiration, he answers by the raising of the ribs and the
descent of the diaphragm ; the ribs are raised by the intercostal
muscles, both external and internal ; here he takes a side in a
controversy which nearly a century later became acute between
Haller and Bamberger, and has from time to time risen up
again ever since. The diaphragm descends by virtue of its
own contraction. Expiration he argues is in ordinary breathing
the mere passive result of relaxation, the ribs falling back into
their place and the contents of the abdomen pushing up the
diaphragm. And he enters into several minor details, such for
instance as the nature of the articulation of the ribs to the
spine, by which their movements are facilitated. The whole
account, as I have just said, might almost have been written
at the present day.

He then proceeds to the larger question, What is the use of
breathing? What effect is produced by breathing?

He ridicules the old and as yet still common view that
breathing serves for cooling the heart. The blood and its
fermentations he says seem to need heat rather than cold.
And violent exercise, even one so brief that the blood has
not time to get overheated, is followed by a much more
intense respiration than is the highest fever.

He rejects the opinion which he aflSrms to be even more
common that breathing is to facilitate the passage of the blood
from the right to the left side of the heart. It is absurd, he
says, to suppose that such an elaborate mechanism is needed for
a mere transit. And indeed that the movements of breathing are

F. L. 13

194 The English School [lect.

not necessary for the transit is shewn by the simple experience
that " when you hold your breath as long as you can the finger
"on the pulse will tell you that blood is still rapidly passing
" into the arteries," and therefore must have made the transit
through the quiescent lungs.

Still another opinion that the blood is agitated, comminuted
and broken as it were into very minute particles, is also according
to him wrong, for any air would produce this mere mechanical
effect, and air vitiated by some contagion or air which had
been breathed over and over again would be equally good for
respiration.

"And indeed if the need of breathing only arose as some
" have thought, in order that the mass of the blood should be
" thoroughly shaken by the movements of the lungs and broken
" up as it were into extremely minute parts, there would be no
" reason why an animal should so quickly expire when shut up
"in a flask in the manner stated. For the air in the flask
" even after the death of the animal is quite as well fitted as
" before for the inflation of the lungs and so for the comminu-
" tion of the blood. For since that air is still subject to the
"pressure of almost the whole atmosphere, there is nothing
" to prevent its being driven into the dilated thorax of the
" animal, it being this, as I have elsewhere said, on which the
"inflation of the lungs depends."

No, he says, it is evident that something belonging to
the air, whatever it be, something necessary for sustaining
life passes from the air into the blood. Hence air which has
been already breathed and which has in consequence been
exhausted of those vital particles, is no longer fit for being
breathed again.

"On the one hand it clearly appears that animals exhaust
" the air of certain vital particles which are* of an elastic nature.
"On the other hand there cannot be the slightest doubt but
" that some constituent of the air absolutely necessary to life
" enters into the blood in the act of breathing.

" We have no right to deny the entrance of air into the
" blood because on account of the bluntness of our senses we
" cannot actually see the vessels by which it makes its entrance.

vn] of the Seventeenth Century. 195

" For other ducts, which serve to carry denser liquids, are not
" visible to the eyes until their several hair-like passages, after
"running a certain distance, join together to form a notable
" canal. What eye has ever been sharp enough to see the first
" beginnings of the lymphatic, or of the lacteal vessels, or even
" of the veins ? " He does not seem to have read Malpighi's
second tract, and Leeuenhoek had not yet made his more
convincing observations. " How much less are we likely to see
*' these aereal ducts, which must be very short and exceedingly
" delicate. For these passages are not like the others, passages
"becoming joined together after running separately for some
" distance ; they only liave to traverse the membranes of the
" lungs, each following a very short and obscure path. For in
"order that the aereal particles should mix with the mass of
"blood in a state of fine division and in a most intimate
"manner, it is necessary that they should enter the blood
" through channels or rather orifices almost infinite in number,
" distributed here and there over the whole mass of the lungs.
" And indeed in lungs which have been prepared and dissected,
"holes, almost without number, like most minute points may
"be seen with the aid of the microscope. Whether however
" those points are the mouths of capillary air tubes or of vessels
" opening into the blood cannot be determined for certain.

"Let us inquire in the next place what is that con-
"stituent of the air which thus passes into the blood, which
" is so necessary for sustaining life that we cannot live for even
" a moment of time without it. And indeed it is very probable
" that certain particles of a nitro-saline nature, and those very
" subtle, nimble, and of very great fermentative power, are sepa-
" rated from the air by the aid of the lungs and introduced into
"the mass of the blood. And so necessary for life of every
" kind is that aereal salt (constituent) that not even plants can
" grow in earth the access of air to which is shut off. But if
" that same earth be exposed to air and so forthwith impreg-
" nated with that fecundating salt, it at once becomes fit again
"for growing. It is clear that even the very plants seem to
" have some need of breathing, some need of drawing air into
" themselves.

13—2

196 The English School [lect.

" What part however this aereal salt plays in animal life it
" is not easy to understand. It is at all events probable that
" the nitro-aereal spirit, mixed with salino-sulphureous particles
" of the blood, excites in it a needed fermentation. We must
" not however suppose that the eflFervescence of the blood takes
" place in the heart alone ; it takes place also in the pulmonary
" vessels before the blood reaches the heart, and afterwards in
"the arteries, no less than in the heart itself."

The word * effervescence ' shews that he had read Sylvius.
Possibly, or perhaps we may rather say probably his acute mind
had, pondering much over fermentations, begun to grasp some
new ideas about these mysterious processes, and had he lived
we might have learnt from him things which did not come until
much later.

Touching thus upon fermentation, he turns aside to note
that he is not forgetful of that ' fermentum ' of a mysterious
character supposed to exist in the left ventricle, the ferment of
van Helmonts fifth digestion; but he scornfully rejects the
idea. Then he passes on to have a tilt with Descartes, who,
great philosopher, but amateur physiologist, as he was, had not
as we have seen grasped the force of Harvey's arguments, and
contended against Harvey that the beat of the heart was an
expansion due to the rarefaction of the ventricular contents.
Mayow had no difficulty in following Harvey and Lower
in the proof that the blood was driven out of the heart by
the contraction of the muscular walls. The heart, he says>
is nothing but a muscle, very little different in its action
from other muscles. And he clenches his argument against
Descartes with two remarkable experiments. "If in the
"heart of an animal just dead, filled not with blood, but
'* with water or some simple liquid, you excite a movement
"like that which takes place in systole, the contents of the
"ventricle are forthwith ejected, not indeed by reason of a
" fermentative explosion, for such in this case certainly cannot
" take place, but simply because the ventricles are contracted."
Besides it is very certain that the movement of the heart can
not be due to the rarefaction of the blood ; for sometimes the
heart, cut clean out of the body, may be seen to beat, although
all the blood has already been driven out of the ventricles.

vn] of the Seventeenth Century. 197

He then goes on to ask the question why death follows
suppression of breathing.

"Life, unless I mistake, consists in the distribution of
** animal spirits, for the supply of which the beating of the
" heart and the flow of blood to the brain are absolutely necessary.
" And breathing seems especially to assist the beat of the heart,
"in a manner elsewhere described. Now it is very probable
"that this aereal salt is wholly necessary for all muscular move-
" ment, so that without it the beat of the heart cannot take
*' place. For we have reason to think that the sudden con*
" traction of a muscle is due to particles of two different kinds
" mixing with each other, and mutually acting upon each other.
"Now we cannot suppose that both kinds of particles, the
" effervescence of which gives rise to the contraction of muscles,
"can come from the mass of the blood, for liquids which are
"derived from the same source unite again without any
"effervescence. So that it seems that something extraneous
"is requisite for bringing about the ebullition which leads to
"muscular movement.

"We may therefore suppose that the nitro-saline particles
" derived from the inspired air supply the one class of motive
"particles which, meeting with the other, salino-sulphureous
" particles furnished by the mass of the blood, but dwelling in
"the motor structures, excite that effervescence which gives
" rise to the muscular contraction, as we have fully shewn else-
" where.

" The movement of the heart is carried out in the same way
" as in other muscles.

" Hence, when breathing is stopped, since that aereal salt,
" needful for all movement, is lacking, the beat of the heart and
" therefore the flow of blood to the brain, are interrupted, and
"death necessarily follows."

This view of the use of the nitro-aereal particles naturally
leads to the corollary that "breathing is increased during violent
*• exercise, not in order that a greater flow of blood may take
"place freely through the lungs, but in order to provide for
" the greater expenditure of the nitro-aereal salts in the many
" effervescences taking place in the contractions of the muscles."

198 The English School [lbct.

His nitro-aereal hypothesis also enabled him to lay hold of a
sound theory of animal heat.

The union of the nitro-aereal particles (taken in by breathing)
with the salino-sulphureous particles of the blood gives rise to
the heat of the blood. The greater heat which accompanies
violent exercise is due to the greater supply of nitro-aereal
particles caused by the increased respiration. This brings
about an increased effervescence, and so. an increase of heat
in the blood itself, but at the same time the heat is also in-
creased by the greater eflFervescence in the muscles themselves.

It will thus be seen that Mayow had laid firmly hold of one
factor of respiration, the entrance of something from the air of
the pulmonary vesicles into the blood. He had not grasped the
other factor now known to us, the exit of something from the
blood into the pulmonary vesicles. He was only on the track
of this. He says, "about expiration is to be noted that this
" serves a further purpose, namely, that together with the air
" driven out of the lungs, the vapour of the blood agitated by
"the fermentation is blown away also." And he developes a
theory, foreshadowing modem views, that it is a feature of the
fermentative action of the nitro-aereal particles that the blood,
when it comes back to the lungs as venous blood, having been
deprived in the tissues of its nitro-aereal particles, is greedy of
fresh particles of that kind, and so assists in drawing them into
the blood out of the air of the lungs. So the fermentation of
the blood is kept up by an automatic, self-regulating process.

I have ventured to dwell at such length on the writings of
John Mayow because they afford a striking example of how
the seed of truth fails to spring up into a plant unless it
fall on congenial ground. By his nitro-aereal, or igneo-aereal
particles, Mayow evidently meant what we now call oxygen.
He saw that this formed only a part of the atmosphere, that
it was essential for burning, that it was essential for all the
chemical changes on which life depends, that it was absorbed
into the blood from the lungs, carried by the blood to the
tissues, and in the tissues was the pivot, the essential factor of
the chemical changes by which the vital activities of this or
that tissue are manifested. It was essential in muscle to the

vn] of the Seventeenth Century. 199

occurrence of muscular contractions, it was essential in the
brain to the development of animal spirits.

This great truth was reached at a time when the men of
chemistry were struggling with the spiritualistic fermentations
of van Helmont on the one hand, and with the material
eflFervescences of Sylvius on the other. It was reached by a
young man of twenty-five years, who died a few years afterwards.

When we look at the portrait aflBxed to his book we see a
face delicate in outline, yet with a firm mouth, the visage of a
man who had spent his as yet short days in the quiet but
earnest and unresting pursuit of truth amid the calm of
academic retirement. His premature death bids us think that
not long after he had made known the results of the labour of
his early years, the beginnings of disease had already made his
spirits droop and his hand hang heavy by his side. Otherwise
he must have had something to say during the ten years which
ran between the publication of his book and his death. Yet he
was silent. Had his body been as strong as his mind was acute,
had he lived to that ripe old age which was reached by many
another leader in science, how diflFerent had been the story of
chemical physiology.

But it was not to be. This bright school of English physio-
logists of the mid-seventeenth century, Boyle, Hooke, Lower,
and Mayow, worthy children of the great Harvey, passed away,
and for a long time none took their place. Though the physical
and experimental work of the three former remained effective
on men's minds, the chemical work of Mayow soon passed out
of ken ; a few passing references, and those for the most part
feathered with scorn, to the supposed part played by nitrous
particles in breathing, supply all that can be found in succeeding
writers. The world had to wait for more than a hundred years
till Mayow's thought arose again as it were from the grave in a
new dress, and with a new name ; and that which in the first
years of the latter half of the seventeenth century as igneo-
aereal particles shone out in a flash and then died away again
into darkness, in the last years of the eighteenth century, as
oxygen, lit a light which has burned, and which has lighted the
world with increasing steadiness up to the present day.

LECTURE VIII.

THE PHYSIOLOGY OF DIGESTION IN THE
EIGHTEENTH CENTURY.

The story, even in outline, of the progress of Physiology in
the seventeenth century has in the preceding lectures been
told in part only. Men's minds in that century were busy with
problems of the animal body besides those of digestion and
breathing; and I have yet to speak of other labours carried
out by men on whom I have already dwelt, as well as of labours
carried out by men of whom as yet I have said little or nothing.
The division, however, of the labour of inquiry which the
progress of science brought about as the years ran on renders it
desirable that I should complete the stories of the progress of
our knowledge of digestion and respiration, so far as I propose
to carry them, before I speak of the advances made in other
branches of physiology. I therefore propose to devote the
present lecture to an account of the more striking researches in
digestion which were carried out in the eighteenth century.

In a preceding lecture I spoke of two men as exerting,
through their large chemical knowledge, an important influence
on the ideas concerning the chemical problems of physiology at
the latter end of the seventeenth and in the early years of the
eighteenth century. On one of these, George Ernest Stahl, I
have already dwelt.

The other man was Hermann Boerhaave, who was bom on
the 3 1st December, 1668, four years before Sylvius's death, at
Voorhout, near Leyden. The son of a minister he was brought

LBCT. vra] Of Digestion, Eighteenth Century. 201

up to follow his father's career, and his early years at the
University of Leyden were largely given up to classical and
oriental studies, though he at the same time eagerly took up
mathematical physical learning in spite of this not being at
that period in much favour at the University. In 1690 he
became Doctor of Philosophy, choosing for the subject of his
thesis *' The distinction between body and mind." An illness,
an obstinate ulcer of the thigh from which he suffered as a lad,
seems to have turned his attention to medicine ; and after his
graduation while preparing himself by theological studies for
his ordination and supporting himself (for his father died early)
by teaching mathematics and by occasional literary work, he
found time to study medicine and the ancillary sciences of
chemistry and botany. Though he seems in these matters
to have for the most part taught himself, attending but few
lectures, he made such progress that in 1693 he obtained the
degree of Doctor of Medicine, not however at Leyden but at
the University of Harderwick. He intended at first to use
this degree merely as an adjunct to his proper career as a
clergyman ; but having been led by his zeal for mathematics
to refute, in a public conveyance, someone who was ignorantly
declaiming against the doctrines of Spinoza, he acquired the
reputation of being an adherent of that heterodox philosopher ;
and either because he feared that this taint of heresy might
lead to diflBculties about his ordination, or because the love of
medical science was becoming stronger in him than the love
of theology, he gave up the idea of the ministry and definitely
threw himself into the practice of medicine. Thus, in the
tangle of human events, Spinoza, by a roundabout way, gave
Boerhaave, and through Boerhaave gave Haller to medicine
and to science.

His talents soon impressed the authorities of Leyden, and in
1701 he was placed in the chair of Medicine left vacant by the
death of Drelincourt in 1697. He was at first not made full pro-
fessor, only lecturer. The power, however, which he shewed as a
teacher rapidly made itself felt ; students flocked to his lectures ;
and the authorities of the University, lest he should be tempted
by offers from elsewhere, increased his emoluments, and gave

202 The Physiology of Digestion [lect.

scope to his unwearied energy and wide knowledge by placing
him in more chairs than one. In 1709 he was made Ordinary
Professor of Medicine and of Botany; in 1715 he became also
Professor of Practical Medicine, and in 1716 Professor of
Chemistry as well. Much sought after as a physician, acute at
the bedside, brilliant as an expositor in the professorial chair,
he was also a great teacher in the sense that in his daily
intercourse with his pupils he was always ready to lay his
mind open before them, and to let them share in his experience
and in his thoughts. At Leyden he laboured all his life. He
was more than once Rector of the University ; and although in
1729 he resigned the chairs of Botany and Chemistry and
allowed himself a leisure which he devoted chiefly to gardening
in a country seat which he had bought, he still continaed to
teach medicine in spite of the diseases which were creeping
upon him in his old age; and at Leyden he died in harness,
full of honour and esteem, on the 23rd September, 1738.

Boerhaave was in almost all respects a dififerent man from
Stahl. A learned scholar, and a sound scientific thinker, he
was too all round a man to be led away by any one idea
however tempting; essentially eclectic in nature, he gathered
truth from every source. Though living all his life in the Uni-
versity in which Sylvius had laboured so long and so strenuously,
though himself versed above his fellows in chemical knowledge,
his work on the subject being for years the great text-book of
the subject, he did not exalt chemistry above anatomy or above
physics. Though drawn to mathematics long before he thought
of medicine, though an ardent student of Borelli s works and
a pupil of the enthusiastic iatro-physicist Pitcairn, who in 1692
had been brought from Edinburgh to occupy for a brief period
the chair of Medicine at Leyden, he did not think that all the
problems of the human body were such as could be solved by
the mere use of formulae and the calculus. Though the
intimate friend of the great anatomist Ruysch, he was not
ready to admit with him that anatomical disposition supplied
the answer to every physiological question. He made use of
anatomy, of physics and of chemistry, but he never allowed one
to exclude the other ; he was ready to apply each one of these

vm] in the Eighteenth Century. 203

sciences to the elucidation of physiological phenomena; and
the width and sagacity of his teaching are reflected in the work
of his great pupil who followed after him, Albrecht von Haller,
of whom I have soon to speak.

Boerhaave cannot be said to have made by his own researches
any striking contribution to our knowledge of digestion. The
part which he played was rather that of the sagacious eclectic
teacher who has made hiiDself well acquainted with all that
others have done, and who criticising, with wide knowledge,
their various views, and pointing out where they are obviously
wrong, gathers together what might seem to a sober mind the
outcome of their various results.

Thus Boerhaave was not an extreme advocate either of the
mechanical school or of the chemical fermentative school, but
he admitted within limits the doctrines of each.

In his works, as for instance in his Institutiones Medicce
(the first edition of which appeared in 1708), which remained
for many years the common text-book of the schools, and the
first part of which was a treatise on physiology, he recognizes
that digestion is in part a solution of some of the constituents of
the food by means of various juices. Saliva, the juice from the
oesophagus, the gastric fluid, which consists in part of a viscous
secretion poured out by the glands of the stomach, and in part
of a thin fluid secreted by the arteries, the bile, the pancreatic
juice, and the intestinal juice, each of these contributes to the
result. But he regards the solution effected by means of these
juices as of the nature of ordinary solution, not of a nature of
fermentation. It is worth noticing that he denies the acidity
of the gastric juice, and speaks of van Helmont's heresy
on this point. Owing to the labours of Sylvius, Stahl, and
others, men's ideas concerning acidity and alkalinity were
becoming much more definite than they had been; coloured
vegetable juices were coming into use as tests of one or the
other; and Boerhaave, while denjdng the acidity of gastric
juice, expresses his wonder that Sylvius, knowing as he did
what an acid was, could ever have thought that pancreatic
juice was acid. It may be added that Boerhaave regarding, in
common with his contemporaries, the supply of nerves to the

204 The Physiology of Digestion [lbct.

stomach as out of all proportion to the movements or sensations
of that organ, believed that a nervous fluid having some share
in the digestion of food was poured into the cavity of the
stomach from the endings of the nerves.

This solution by means of juices was, however, in Boerhaave's
opinion only a part of the digestive process. He joined with
the mechanical school in believing that the more fluid and
nutritious parts of various articles of food were expressed, from
them by trituration in the stomach. He expressly taught that
the more solid and resisting framework of both animal and
vegetable food was not digested at all ; that digestion to a large
extent consisted in this, that by the solvent action of the juices
or by mechanical pressure the softer or more fluid material held
by the framework was either dissolved or pressed out of it.
In particular he thought that bones were not digested, only
crushed, and pointed to the white excrement, the album graecum,
of dogs fed on bone, as a proof of this.

Boerhaave's positive mode of thinking put him more or less
in antagonism to the doctrines of fermentation, to which, as we
have seen, the chemical school were so attached. He seems,
moreover, to have distinguished between the chemical eflFer-
vescence of Sylvius and true fermentation, such as that of wine.
He regarded the action of the juices as a mere solution, not as
a proper fermentation. Nevertheless he held that solution and
trituration are, in digestion, aided by something else. He
thought that in the stomach, which is a closed chamber, but
with air present in it, the contents, exposed as they are to a
considerable heat, do undergo "an incipient fermentation, by
"means of which the chyle is impressed with the primary
'* principle of vitality."

Such were the doctrines taught by Boerhaave in the early
years of the eighteenth century. They were very largely
accepted, and indeed became the dominant views. We find
almost the same teaching nearly fifty years afterwards when we
come to Haller, of whom we must now speak.

The year 1757 may be regarded in a certain sense as a red
letter year in the history of physiology, as marking an epoch, as
indicating the dividing line between modern physiology and all

vra] in the Eighteenth Century. 205

that went before. It was the year in which the first volume of
the Elementa Physiologice of Haller was published, the eighth
and last volume leaving the press in 1765.

Albrecht von Haller, descendant of an old Swiss family, was
bom at Bern on 18th October, 1708. Precocious as a child he
while yet young acquired a large knowledge both of literature
and science, the former at first being dominant in him and
leading him to the composition of many juvenile poems. Losing
his father while yet a lad of thirteen he continued his education
for some time at Bern, but in 1723 entered the University of
Tubingen. In 1725, however, attracted by the renown of
Boerhaave he moved to Leyden ; and there undoubtedly he
laid the foundation of all his future work. At that time
Boerhaave was in the fulness of his power, the ripeness of his
experience adding more than might seem to be lost through
the declining energy of advancing years ; and he had now by
his side the younger Albinus, Frederick Bernard Albinus, an
accomplished and sagacious anatomist, who later on, in 1745,
became Professor of Anatomy. Under these influences the
young Haller not only made rapid progress, but also had his
versatile mind fixed in its proper direction. Taking in 1727
his degree as Doctor of Medicine at Leyden, upon a thesis in
which he exposed the error of Coschwitz, professor at Halle,
who had maintained that he had discovered a new duct of the
submaxillary and sublingual glands, Haller spent some time in
foreign travel. He visited Belgium, England, where he became
the friend of Sir Hans Sloane, and France, and in 1728 took
up for a while his abode at Basel, studying under the celebrated
mathematican John Bernouilli, and beginning to devote his
attention to systematic botany, at which he continued at
intervals to labour all his life.

In 1730 he returned to his native city; and here for a while
he taught anatomy and practised medicine, prosecuting all the
while anatomical and physiological researches and spending his
leisure hours partly in botanical explorations, partly in composing
poems.

In 1736, the fame of him as a rising man had grown so
great and spread so far that George II. of England, as Elector

206 The Physiology of Digestion [lbct.

of Hanover, possibly instigated by Hans Sloane, created for
him and otFereri to him a chair of anatomy, botany and medicine,
in the University of Gottingen. Haller accepted the offer, and
here, at Gottingen, for seventeen years he laboured, making
physiology the chief duty of the chair. Here he carried out
the most important of his inquiries and gathered together the
material for most of his literary work.

He received several tempting ofifers to accept office in other
Universities, in Oxford, Berlin and elsewhere. These he refused;
but in 1753 feeling that the increase of years, aided by the
climate of Gottingen, was telling upon his health, and he had
never been robust, he withdrew to his native city Bern, there to
spend the rest of his days in leisurely retirement.

Here or in some neighbouring part of Switzerland he lived
for nearly a quarter of a century, refusing to be tempted back
to Gottingen or to go elsewhere, taking his part in municipal
and other duties, completing his Elementa and his other works
of compilation or exposition, giving finishing touches to experi-
mental inquiries, and, by way of relaxation, continuing his
botanical studies and composing poems and literary essays.
Disease however ^ot increasing hold of him, severe pain led
him to the constant use of opium, and his medical friend having
in 1776 foretold that his death would take place in the following
year, he made good the prophecy by quietly passing away on
Dec. 12, 1777. He died, true to the errand of his life, with his
finger on his pulse, his last words to the friend at his bedside
being "The artery no longer beats."

I do not propose now to speak of Haller's many and varied
original inquiries, or of the gains which came to physiology
thereby. He put his hand to the solution of many questions
spread over nearly the whole of physiology ; and in the preface
to the sixth volume of the Elementa he gives a list of what
he claims as some of his own discoveries. Of the highest
importance were his researches on the mechanics of respi-
ration, on the foraiation of bone, and on the development of
the embryo; the latter indeed stands out as the most con-
spicuous piece of work on this subject between Malpighi
and von Baer, though marred by the theoretical specula-

vrn] in the Eighteenth Century. 207

tions attached to it. Of what is perhaps his greatest work,
the establishment of the doctrine of muscular irritability, I
shall have occasion to speak in detail in a succeeding lecture.
For the present I wish to speak of him as an expositor only.
When we turn from any of the preceding writers on physiology,
from any one of those whom I have mentioned in the foregoing
lectures, and open the pages of Haller s Elementa, we feel that
we have passed into modem times. Save for the strangeness
of much of the nomenclature, and for no small deficiencies in
all that relates to the chemical changes of the body, we seem
to be reading a modem text-book, a modern text-book of the
most laborious and exhaustive kind. Haller passes in review all
the phenomena of the body. In dealing with each division of
physiology he carefully describes the anatomical basis, including
the data of minute structure, physical properties, and chemical
composition so far as these were then known. He then states
the observations which have been made, and in respect to each
question as it arises explains the several views which have been
put forward, giving minute and full references to all the authors
quoted. And he finally delivers a reasoned critical judgment,
expounding the conclusion which may be arrived at, but not
omitting to state plainly when necessary the limitations which
the lack of adequate evidence places on forming a decided
judgment. He carefully recounts and as carefully criticises all
the knowledge which can be gleaned about any question. If he
feels unable to come to a decided conclusion he candidly says so.
He always strives to be as exact and as clear as possible ; con-
spicuous is the absence from his writings of loose expressions
and ill-defined general views such as abound in so many of his
predecessors. We may take any part of his great work as a
trustworthy account of the knowledge of the time with regard
to the questions therein treated.

The following is a brief sketch of the exposition which he
gives of digestion. According to him saliva is neither acid nor
alkaline; and so far from attributing to it the great virtues
claimed for it by Sylvius and Stahl, he seems to regard its great
use as being that of softening the food and helping deglutition.
In the stomach he recognizes the importance of the tunica villosa.

208 The Physiology of Digestion [lbct.

consisting of glands which, very obvious in birds, are not so
evident in man; but he thinks that these glands furnish the
mucus of the stomach only, the true gastric juice, succus
gastricus, ventriculi succus, being secreted by the arteries.
The more exact knowledge of nervous action, which, owing
largely to his own labours, had been gathered in since Boer-
haave*s days, led him to discard the idea that a nervous fluid,
oozing from the endings of the nerves, intervenes in gastric
digestion.

Dwelling on the diflSculty of obtaining gastric juice in a
pure condition, noting that acidity is often a token of the
onset, and alkalinity of the advance of putrefaction, he concludes
that pure gastric juice is neither acid nor alkaline ; and while
speaking of it as a macerating liquor which softens and dissolves
the food, he refuses to regard it as a ferment. It is not a
corrosive liquid, as are many acids, and though it may be at
times acid, the acidity is a token of the degeneration of the
digested food, not of digestion itself, which "imparts to the
" food a wholesome animal nature,*' i,e. gives it the beginning of
vitality; and the characteristic of living animal tissues is, he
urges, alkalinity rather than acidity.

Trituration he regards as a useful aid, especially where
hard grains form a part of food, as in that of birds, but only an
aid. "They have done well who have brought back to its
"proper mediocrity the power of trituration so immensely
" exaggerated."

His account of bile shews how much advance had taken
place, through repeated quiet work, in the preceding years.
Bile he insists is not as some have thought a mere excrement.
Retained for a while and slightly altered during its stay in
but not formed by the gall-bladder, secreted on the contrary
by the substance of the liver, partly perhaps from the blood
supplied by the hepatic artery but mainly from that of the
vena porta, bile is a fluid viscid and bitter but not acid, and
indeed not alkaline, a fluid which as all know has the power
of dissolving fat and so acts on a mixture of oil and water
as to form out of them an emulsion ; it thus dissolves all the
food into the homogeneous magma which is called chyle. If,

vra] in the Eighteenth Century. 209

he says, you ligature the duodenum just above the entrance of
the bile duct, you will find the food above the ligature in the •
form of grey lumps, below the ligature in the form of a whitish
homogeneous mass. He adds the notable remark that bile must
have some other function than that just described ; for animals
deprived of their gall-bladder very rapidly perish, the exact
cause of their death not being clear.

Turning to the pancreas, after remarking that the exagge-
rated views of Sylvius and De Qraaf had long ago been refuted
by Brunner, he insists on the importance of the fact that its
duct opens into the intestine in common with the bile duct.
"All which things being considered, a part at least of the
"usefulness of pancreatic juice will be to dilute and soften the
"cystic juice * * * so that this mixes better with the food.
" Whence you may explain the hunger of the animals from
"which the pancreas has been removed, attributing it to the
" reflux of a sharper bile into the stomach." And he ends with
this saying, prophetic of the work of Bernard a hundred years
later, " There may be other functions of the liquid not as yet
" well known to us." Of the intestinal juice and of the other
later changes taking place along the alimentary canal, he says
nothing to which I need call attention ; he seems to think that
the chief event taking place in the intestines is the separation
and absorption of the nutritive constituents, prepared for this
by the action of the stomach and the bile.

It will not have escaped attention that the eflfect of the
labours of nearly the whole of the seventeenth century and of
the eighteenth century up to Haller's time was on the whole
to depreciate the work of the stomach. In van Helmont*s eyes,
the stomach was the great digestive organ, and the acidity of
the gastric juice was its strong hand. Succeeding writers like
Sylvius and Stahl insisted on the greater importance of other
juices, and almost all of them, even those who attributed con-
siderable potency to the gastric juice, denied or at least doubted
its acidity. But the avatar of the gastric juice was beginning
even while Haller was writing his great work.

Ren^ Antoine Ferchault de Reaumur stands out as one of
the most striking men of science of the eighteenth century, and
p. L. 14

210 The Physiology of Digestion [lbct.

indeed, in some respects, of all time. Bom in 1683 at Rochelle
in France, he was educated for the profession of the law;
but possessed of an ample fortune he was under no need
to follow that or any other bread-winning career. Removing
to Paris at the beginning of the eighteenth century, he used
the opportunities which his abundant means aflForded him to
carry out many and varied scientific investigations. Of most of
these I have no occasion to speak here. I need not dwell on
his labours in connection with the manufacture of steel. I
need Dot speak of the thermometer which bears his name, and
which he invented in 1731. Nor shall I here even discuss his
great work on Insects, published during the years 1734 — 1742,
though this contains much of physiological interest. I must
content myself with pointing out the important results em-
bodied in his treatises on the Digestion of Birds (Sur la
Digestion des Oiseaux) which appeared in the " Memoirs of
"the Academy of Science of Paris" in 1752.

The problem which he put before himself in this research
was : — Are the changes which the food undergoes in the stomach
to be regarded as the results of mere trituration, or of a sort of
putrefaction, or are they those of solution, effected in some way
or other by means of the gastric juice secreted by the stomach ?
Having in his possession a Kite he took advantage of its well-
known habit of rejecting from its stomach things swallowed,
such as feathers, which it could not digest. He made use
of small metal tubes open at both ends, save that each end
was secured with a grating made of threads or fine wire. He
gave the Kite some of these tubes, filled with pieces of meat,
and he found that when they were rejected the meat had been
partially dissolved, but exhibited no odour or other signs of
putrefaction. Small fragments of bone similarly introduced
into the stomach in metal tubes were also found to be dissolved.
The pieces of bone were only partially dissolved, but by giving
the same pieces of bone a second and a thii'd time in the
same way he found that at last they were almost completely
dissolved. But while meat and bone were thus dissolved,
vegetable grains or flour similarly exposed in tubes to the
action of the stomach, seemed to be little altered. He further
observed that the tubes when rejected were more or less filled

vm] in the Eighteenth Century. 211

with a yellowish, somewhat opalescent fluid, which to the taste
was salt and bitter. Obviously it was this fluid which dis-
solved the meat and bone. And he put to himself the question,
" What then is this liquid which acts on meat and on bone in
" some such way as leau regale acts on gold, but has not the
"same power over starch (farina) that Veau regale has over
" silver ? To which of the solvents which chemistry offers us
" can this liquid be compared ? "

To answer this question he filled his tubes with small pieces
of sponge, from which, when rejected, he squeezed out the fluid
which they had imbibed. In this way he obtained a quantity,
on one occasion 63 grains, of an opalescent fluid, salt to the taste
rather than sour, a fluid " which turned blue paper red/' By
help of this contrivance he was the first to obtain gastric juice
in an approximately pure condition.

With this fluid he attempted to digest in vitro. He exposed
pieces of meat to the action of it at 32° R. for 24 hours, using
similar pieces of meat placed in simple water as a control. His
first experiment was wholly a failure. In a second experiment
while the control putrefied, the meat in the gastric juice though
not very much dissolved was hardly at all putrefied. Digestion
therefore was not putrefaction but something actually opposed
to that process.

At this stage unfortunately his Kite died and his experi-
ments were stopped.

He continued his investigations, making use of other animals.
He gave to a dog some bones, and also some of his tubes con-
taining meat. On killing the dog 24 hours afterwards, he found
the bones not crushed but partly dissolved and much altered ;
the meat in the tubes also was much dissolved though the
tubes themselves were hardly or not at all distorted, and there-
fore had not been crushed. Some further experiments in which
he made sheep swallow tubes filled some with chopped green
herbs, others with chopped hay, and examined the contents of
the tubes by killing the animal and finding them in the paunch
14 hours afterwards, or by waiting until they had been voided,
gave dubious or rather negative results. The contents of the
tubes were not greatly altered.

14—2

212 The Physiology of Digestion [lect.

Reaumur's investigation left much still to be ascertained;
nevertheless he established by direct experiment that the fluid
in the stomach, the gastric juice, had a distinct solvent power,
that it dissolved various constituents of food, and did so not by
inducing or favouring putrefaction, but by some process which
was antagonistic to putrefaction. And he arrived at his results
by the employment of a wholly new method.

Though his results attracted attention and are referred to
by Haller in his Elementa, no one for some time followed his
line of investigation or adopted his methods. We have to wait
for more than a quarter of a century before any fresh real
addition to our knowledge of digestion took place. And for
this physiology went back once more to Italy.

In the ye^r 1729 there was bom at Scandiano near Reggio
in Southern Italy Lazaro Spallanzani, the son of a distinguished
advocate. He received a very liberal education in letters, being
intended by his father for the profession of law, but Vallisnieri,
then Professor of Padua, persuaded the father to allow the son
to follow in his studies the bent of his mind, which was clearly
towards natural science and especially natural history. The
celebrated Laura Bassi, then holding, though a woman, the
chair of mathematics at Bologna was his cousin; he studied
under her and her teaching seems to have confirmed his love
for science. In 1754 he became Professor of Logic, Mathematics
and Greek at Reggio, but in 1760 was transferred to Modena to
fill the chair of Natural History. In 1768, the empress Maria
Theresa, who was developing and indeed re-establishing the
University of Pavia, invited him to become professor there of
natural history ; and he accepted the offer. He was pressed in
1785 on the death of Vallisnieri to succeed that great naturalist
in the chair of Natural History in the University of Padua ; but
he refused, taking advantage however of the invitation to obtain
leave for a long travel in Turkey. By specimens obtained in
this and in his other many travels he enriched the museum of
the University of Pavia, to which he remained devoted. He
died in that city on Feb. 3, 1799. In the course of his educa-
tioni before his appointment at Reggio he had taken orders in
the Church, and is frequently spoken of as the Abb6 Spallan-

vm] in the Eighteenth Century. 213

zani ; but nearly the whole of his energy was thrown into the
investigation of problems of natural history. His works on
Reproduction brought him great fame ; his contributions to the
physiology of the circulation were considerable; he travelled
much and worked at geological problems ; and just before his
death he carried out researches on respiration in which he made
a notable addition to that part of physiology for which Lavoisier
had just done so much. But here I wish to speak only of his
contributions to the physiology of digestion, his first memoir on
which was published in 1777, the year of Hallers death, others
following in the succeeding years.

He took up again Reaumur s method, and most of his results
were gained by it, though he also adopted other methods.
Finding the knowledge of the subject almost in the condition in
which Reaumur had left it, he was able by his numerous experi-
ments, aided by the improvements in chemistry since Reaumur's
time, to make a great advance over his French predecessor.

He experimented with all kinds of animals (and he was it
may be noted not a mere physiologist but a naturalist, one
who studied animals (and plants) from various points of view),
fishes, frogs, newts, serpents, birds of various kinds, sheep, oxen,
horses, cats, dogs, and lastly himself He at least ran no
risk of going astray by making deductions based on results
gained with one kind of animal only.

He employed largely as I have said Reaumur's method.
He made use of metal tubes, closed by a grating at each end ;
but in order to allow the freer entrance of fluid he also made
perforations in the walls. Sometimes he used hollow spheres
made of two hemispheres screwed together, the walls being
freely perforated. These tubes or spheres he filled with pieces
of meat, bread or bone, or grains of wheat and the like. He
recovered them in the case of carnivorous birds through their
being rejected by the mouth ; in the case of other animals he
opened the stomach after the lapse of a given time.

He also made animals swallow pieces of meat or the like,
so attached to threads or wires that he could after a while
withdraw them from the stomach.

On himself he experimented by swallowing small linen

214 The Physiology of Digestion [lect.

bags containing meat, bread, &c., and examining the contents
after they had been voided per anum. Greatly daring he
swallowed perforated tubes, made not of metal but wood ; and
these he successfully recovered without suflfering any harm.

He obtained what he speaks of as gastric juice by making
animals swallow on an empty stomach tubes containing sponges.
On recovering the tubes he found that the sponges had imbibed
a considerable quantity of fluid, which he squeezed out. From
himself he obtained gastric juice by making himself vomit on
an empty stomach before breakfast ; but this mode of experi-
mentation was he says so disagreeable that after two trials he
gave it up.

The action of the gastric juice so obtained he tested on
various articles of food in vitro, exposing tubes containing the
juice and food to warmth either by keeping them in his own
armpit for two or three days, or by placing them in a stove,
and always using as a control the same food covered with simple
water.

By a very large number of experiments carried on in these
various ways he confirmed and greatly extended Reaumur's
results. He found that in all animals food is in the living
stomach dissolved " into the pultaceous mass called chyme " by
the juice to whose action it is there subjected; and that this
juice is a solvent of all kinds of food, animal and vegetable,
bone included, though some things or parts are more soluble
than others. He found that the juice was more active on
divided parts, such as crushed grains, or broken bones, than on
whole solid parts, such as whole bones, or whole grains ; from
this he concluded that "trituration is merely a preparation
"for solution and does not itself constitute the digestive
"process." He was led by his numerous experiments to the
same conclusion as Reaumur, that while gastric juice was a
solvent of all kinds of food, the juice of this or that animal
was more specially active on the natural food of the animal,
that the juice of the herbivorous animal for instance was more
active on vegetable food. Recalling Reaumur's experiment of
giving green plants or hay to sheep in tubes, he repeated the
experiment and obtained at first similar negative results, even

vmj in the Eighteenth Century. 215

in the case of tubes which had passed into the fourth stomach.
But, remembering that the sheep always ruminated, and pre-
pared its food for sohition by prolonged mastication, he repeated
the experiment with the variation that he carefully masticated
the food, herbs or hay, before he introduced it into the tubes.
He then found that the contents of the tubes were largely
dissolved. He concluded that mastication, with the attendant
admixture of saliva was like the trituration in the muscular
stomachs, a preparation for the solvent action of the gastric juice.

His experiments with gastric juice removed from the living
stomach and made to act on food in vitro fully confirmed the
results obtained in the living stomach itself Food of very
various kinds thus exposed to the action of gastric juice was
dissolved and did not putrefy, whereas the same food subjected
to the action of simple water soon putrefied. Solution in vitro
was however never so rapid or complete as in the living
stomach. Thinking that this might be due to the fact that in
the experiment out of the body the gastric juice is not renewed
as it is in the living stomach, he endeavoured to imitate the
natural process by allowing his gastric juice to fall drop by
drop on, and to run away drop by drop from, pieces of meat and
bread. He now found that " solution took place with exceeding
" speed." He observed that in all cases heat favoured solution ;
indeed in warm-blooded animals a certain high temperature
seemed to him necessary, though cold-blooded animals did not
need this.

It was clear from his experiments that gastric juice was a
powerful solvent of all kinds of food. The question now arose,
What was the nature of this solvent power? "It remains,"
says he, "to be inquired whether this function is connected
" with a principle of acidity, as some suppose, or of putrefaction
" according to others."

The supposition of putrefaction was soon disposed of; so
far from producing or even assisting putrefaction, the gastric
juice was actually opposed to putrefaction; meat which in
simple water readily putrefied in the warm, remained sweet in
gastric juice kept equally warm: the gastric juice even de-
stroyed the putridity of putrid meat.

216 The Physiology of Digestion [lect.

Putrefaction in Spallanzani's time, as of old, was regarded
as one of the modes of fermentation; but by his time the
general ideas about fermentation had become more clearly
defined. It was no longer confounded with the effervescence
due to mere chemical action. "There are,*' says Spallanzani,
*' three kinds of fermentation : the vinous or sweet, the acetous,
"and the putrid." The action of the gastric juice was not a
putrid fermentation ; could it be one of the other two ? He
was inclined to believe that the action could not be considered
as any kind of fermentation at all, because bubbles of air
formed a necessary feature of every fermentation in a liquid,
and solution by gastric juice could and generally did take
place without any bubbles of gas being formed. The action
certainly was not a vinous fermentation, since neither gas nor
alcohol was formed. Could it be of the nature of acetous
fermentation? In discussing this Spallanzani enters on the
question whether gastric juice is acid.

It will be remembered that though van Helmont had put
in the foreground the acid nature of the digestive fermentation
taking place in the stomach, succeeding writers had denied
this and did so as time went on with increasing assuredness,
though Spallanzani as we have just seen referred to its being
still maintained by some. Spallanzani's results led him to
agree with the dominant view. It may here be remarked
that when Spallanzani speaks of gastric juice he means some-
thing which he regards as a mixed fluid. The juice which he
squeezed out of the sponges contained in the tubes recovered
from the stomach he describes as * a transparent yellow fluid
" which gave very little sediment on standing, which had
" a taste intermediate between bitter and salt, which was not
"very volatile and which certainly contained no inflammable
"components." When on the other hand he opened the
stomach of dogs and examined the liquid which oozed out
from the surface of the lining mucous membrane, he found
that this was "colourless, insipid and very thin," thus con-
trasting with that which is generally found in the interior
of the cavity of the stomach when opened, this being yellow,
bitter and somewhat gelatinous, like the material imbibed by

vra] in the Eighteenth Century, 217

the sponges in the tube. Hence he inferred that what he
called gastric juice was a mixture consisting of the above
proper secretion of the stomach, " thin, colourless and insipid,"
together with saliva, juice secreted by the glands of the
oesophagus, bile and possibly pancreatic juice; bile seemed
to be always present in his specimens of gastric juice and to
this he attributed the bitter taste. The activity of this mixed
juice was probably due to the constituent supplied by the
stomach itself* for when he introduced into birds, such as
crows, two pieces of meat fastened on a wire so that the
lower one reached the stomach but the upper remained in
the oesophagus, the former was much more readily dissolved
than the latter; similarly when he introduced a long rod of
meat reaching through the oesophagus into the stomach,
this was much corroded at the end which reached into the
stomach, but very little above. But he did not follow up
the investigation into the properties of pure gastric juice,
and contented himself with the results obtained from the
mixed contents of the stomach.

He repeatedly tried to obtain evidence of the presence
of acids in this mixed gastric juice but failed to obtain
anything which could satisfy him. Though he observed that
shells and corals were corroded in the stomach of birds, he
could not find any clear indication of acidity in the stomach
other than that which was due to the tendency of food to turn
sour; and this says he is an abnormal and not a healthy
condition.

" I repeatedly dropped gastric juice upon salt of tartar per
" deliquium, and into the nitrous and marine acids without ever
" perceiving any change of colour, any motion or eflfervescence ;
" whence I am obliged to infer that the gastric juice is neither
"acid nor alkaline, but neutral." His own gastric juice,
obtained as we have seen by vomiting, he also found to be
neutral ; and he is confirmed in his belief that acidity of the
gastric juice is something abnormal by the reflection that
regurgitation of sour material from the stomach into the
mouth only occurs when digestion has gone wrong; and he
quotes his own experience of acid fluid coming up into his

218 The Physiology of Digestion [lbot.

mouth after a too great indulgence in strawberries and white
wine, which had obviously disagreed with him.

It will be interesting to quote here what is perhaps the
earliest analysis of gastric juice. Spallanzani asked his colleague
and friend, Scopoli, Professor of Chemistry at Pa via, to examine
for him the gastric juice which he had obtained from crows
by his sponges and tubes. This is what the chemist reports.
"The fluid contains first pure water, secondly a saponaceous
"and gelatinous animal substance, thirdly sal ammoniac, and
"fourthly an earthy matter* like that which exists in all
"animal fluids. It precipitates silver from nitrous acid and
" forms luna cornea. This phenomenon might induce us to
"suppose that common salt exists in the gastric juice; but
"the salt contained in this fluid is not common salt, but
" sal ammoniac."

Spallanzani thus came to the conclusion that gastric juice
is not acid, though he asked himself the question whether
since it curdled milk it might not contain "an acid in some
"latent form."

Since then gastric juice was not acid, solution of food by
its means could not be of the nature of acetous fermentation
any more than it was of the nature of vinous or putrid
fermentation. It was not any of the known forms of ferment-
ation ; it was not a fermentation at all.

We thus owe to Spallanzani, after Reaumur, the definite
experimental proof of the solvent power of gastric juice over
various constituents of food. But he was unable to go beyond
this, because he failed to recognize its acid character; he
could only say that the action was not a fermentation in the
then usual sense of that word ; he could not explain how this
apparently neutral fluid possessed these solvent powers. We
may wonder how so acute an observer missed the acidity of
gastric juice. We may partly explain this by the fact that he
confined his tests for acidity to the gastric juice which he had
obtained from fasting stomachs, including that obtained from
himself, and apparently did not test the juice which had
actually digested the material contained in his tubes. Still
in some or other of his almost innumerable experiments he

vm] in the Eighteenth Century. 219

must, we might fancy, have come upon evidences of acidity
so distinct that he could not overlook it. Possibly even he,
accurate and unbiassed observer as he certainly was, may have
been misled by preconceived opinion; when he came upon
acidity he regarded it as something abnormal.

Be it as it may, by Spallanzani's labours, the fact of
the solvent power of gastric juice as a power which was sui
generis, the solution effected by which was not the solution of
putrefection, or of any other known form of fermentation such
as might occur under various circumstances, whether within
or outside the stomach, became an established fact, a definite
addition, never afterwards taken away to our knowledge of
digestion.

I ought to add that in an Inaugural Dissertation which
appeared in the same year as Spallanzani's first memoir, namely
in 1777, Stevens of Edinburgh, adopting Reaumur s methods,
had arrived at results similar to those of the French and
Italian inquirers. Taking advantage " of a man of weak under-
" standing who gained a miserable livelihood by swallowing
"stones for the amusement of the common people," Stevens
made him swallow silver perforated spheres containing pieces
of food, animal and vegetable, raw and cooked and including
bone; he found on examining the spheres, when after some
forty-eight hours they were voided, that the food was for the
most part dissolved ; whole grains however of wheat, peas, &c.
were but little changed. He continued his experiments on
dogs, making them swallow similar spheres, killing them after
a variable number of hours and opening their stomachs. He
repeated the experiments on sheep and oxen, and found that
while these digested readily vegetables, hay and herbs, their
stomachs had little action on animal food. He then obtained
'pure gastric fluid* from the stomach of a dog killed after a
fast of sixteen hours, and found that this fluid at a temperature
of 102 — 104° Fahr. readily dissolved cooked meat, without any
putrefaction and without any development of air bubbles. He
thus came with Spallanzani to the conclusion that digestion " is
" not the effect of heat, trituration, putrefaction or fermentation
" alone, but of a powerful solvent secreted by the coats of the

220 The Physiology of Digestion [lect.

"stomach which converts the aliment into a fluid resembling
"the blood." He adds, "It is probable that every species of
"animal has its peculiar gastric liquor capable of dissolving
" certain substances only." The conclusions are almost identical
with those of Spallanzani, but did not attract so much attention
as did those of the Italian philosopher.

About the time that Spallanzani was conducting his re*
searches on digestion, the great English Surgeon John Hunter
was also turning his attention to the same subject. In 1772
he published in the Philosophical Transactions a paper
"On the Digestion of the Stomach after Death"; and his
"Observations on Certain Parts of the Animal Economy,"
the first edition of which appeared in 1786, contains a memoir
entitled " Observations on Digestion." In the latter publication
Hunter went out of his way not only to say that a statement
by Reaumur which he quotes "is to be set down as a piece
" of anatomical ignorance," but also to criticise severely several
particular experiments of Spallanzani as well as his general
method of inquiry. He complained of Spallanzani as being
deficient in anatomical knowledge, and in that "like all mere
" experiment-makers, he is not satisfied even with those which
" are clear and decisive, but multiplies them most unnecessarily."
He explained how in his view experiments ought to be con-
ducted and adds that "if Spallanzani had employed half his
"time in this way * * * he had employed his time much
" better than in making experiments without end." This rude
and disdainful criticism Spallanzani answered and adequately
rebuked in a dignified manner in a letter published in 1788.
One cannot help suspecting that the tone of Hunter s remarks
was in part at least due to a want of sympathy between
Spallanzani's general views and his own. For Spallanzani
was eminently free from all vitalistic tendencies. On the other
hand, to understand Hunter*s views it must be borne in mind
that he distinctly belonged to the school of Stahl though he
replaced the phrase ' sensitive soul ' by that of * vital principle.'

"An animal substance," says he, "when joined with the
" living principle, cannot undergo any change in its properties
" but as an animal ; this principle always acting and preserving

vm] in the Eighteenth Century, 221

" the substance possessed of it from dissolution, and from being
"changed according to the natural changes which other sub-
" stances undergo." The doctrine here laid down is, it will be
observed, almost identical with that of Stahl.

In his first paper Hunter states that *' the appearances of
"the stomach found to be digested after death shew that
" digestion neither depends on a mechanical power, nor contrac-
" tions of the stomach, nor on heat, but on something secreted
" in the coats of the stomach, and thrown into its cavity, which
"there animalizes the food or assimilates it to the nature of
" blood.*' The instances of the stomach digesting itself interested
him, because he maintained that " animals or parts of animals,
" possessed of the living principle, when taken into the stomach,
" are not in the least aflfected by the powers of that viscus, so
" long as the animal principle remains." And he explained the
auto-digestion as due to the walls of the stomach ceasing to be
alive and becoming subject to the power still remaining in the
gastric juice which they had themselves secreted.

Hunter is very clear that digestion is not fermentation.
He speaks of the vinous and acetous fermentation to which
vegetable substances are prone and of the putrefactive fermenta-
tion to which animal substances are subject. And he argues
as follows: — "It may be admitted as an axiom that two processes
** cannot go on at the same time in the same part of any
" substance ; therefore neither vegetable nor animal substances
"can undergo their spontaneous changes while in the act of
" being digested, it being a process superior in power to that of
"fermentation. * * ♦ The gastric juice therefore preserves
" vegetables from running into fermentation and animal sub-
" stances from putrefaction ; not from any antiseptic quality in
" the juice, but, by making them go through another process,
" preventing the spontaneous change from taking place.''

And he developes his view more fully as follows: "The
" process of digestion diflfers from every other natural operation
" in the change it produces on different bodies ; yet it is by no
"means fermentation, though it may resemble it. For fer-
" mentation, a spontaneous process, is that natural succession
"of changes by which vegetable and animal matter is reduced

222 The Physiology of Digestion [lect.

"to earth; therefore must be widely different from digestion
** which converts both animal and vegetable substances into
"chyle, in the formation of which there cannot be a de-
" composition similar to fermentation.

"Digestion is likewise very different from chemical solution,
" which is only a union of bodies by elective attraction. But
"digestion is an assimilating process; and in this respect is
"somewhat similar in its action to that excited by morbid
" poisons. It is a species of generation, two substances making
" a third ; but the curious circumstance is its converting both
" vegetable and animal matter into the same kind of substance
" or compound, which no chemical process can effect. The chyle
" is compounded of the gastric juice and digestible substances
"when perfectly converted; and it is probable that the quantity
" of gastric juice may be nearly equal to that part of the food
" which is really changed into chyle."

Hunter's views here it will be seen are very similar to those
of Spallanzani, though modified by the vitalistic Stahlian
conceptions in which the latter did not share. In one respect
Hunter went beyond Spallanzani ; he was, at least at one time,
inclined to attach importance to the acidity of gastric juice.
In 1772 he says: "In all the animals, whether carnivorous or
" not, upon which I made experiments to discover whether or
" not there was an acid in the stomach (and I tried this in a
"great variety), I constantly found that there was an acid,
" though not a strong one, in the juices contained in that viscus
" in a natural state." But in his later paper he is led to think
that " it is only formed occasionally. Whether the stomach
"has the power of immediately secreting this acid, or first
" secretes a sugar which afterwards becomes acid, is not easily
" ascertained." He is inclined towards the latter view, especially
since in the stomach of the calf before birth no acid can be
found. And indeed the eighteenth century passed wholly away
before the ' acid ferment * on which van Helmont had, in the
early years of the seventeenth century, laid such great stress
was rightly appreciated. For the observation of Carminati, who
following close after Spallanzani, in 1785 found the clue to the
problem of the acidity of gastric juice, by shewing that in

vm] in the Eighteenth Century. 223

carnivora at least the juice though neutral when the animal
is starving, is undoubtedly indeed strongly acid after it has
been fed, fell on barren ground, and failed to produce the fruit
which otherwise it might.

During the two centuries, the seventeenth and the eighteenth,
physiological inquirers, as we have seen, swayed now in one
direction, by views of chemical fermentation or effervescence,
now in another direction by views of mechanical trituration,
had come in the end to the conclusion that digestion was in
the main a process of solution of a peculiar character begun
and chiefly carried out in the stomach though assisted by
minor subsequent changes taking place along the intestines.
They who were under the influence of the Stahlian vitalistic
doctrines, and these were perhaps the more numerous, held the
change to be the commencement of, to be the first step in,
the conversion of dead food into living flesh and blood, and
spoke of it as an animalisation. They who were not of that
school were content to speak of it as a change differing
from ordinary chemical change, without being able to define
its exact characters. It was left for the nineteenth century
to throw a new light on the nature of the gastric changes and
at the same time to shew that what took place in the stomach
was not the whole of digestion, but only the first of a series of
profound changes taking place along nearly the whole length
of the alimentary canal.

LECTUKE IX.

THE RISE OF THE MODERN DOCTRINES OF
RESPIRATION. BLACK, PRIESTLEY, LAVOISIER.

We have seen in a preceding lecture how far John Mayow
went in the knowledge of the chemistry of breathing. He
wrote in the third quarter of the seventeenth century ; and by
the end of the century his views had well-nigh passed away
from men's minds. Some writers it is true still spoke of
* nitrous particles ' playing a part in breathing, but the ideas
which were thus put forth were more akin to the loose notions
which we have seen Sylvius held, than to the clear and definite
conception of Mayow. We have dwelt, in a preceding lecture,
on the chemical activity of Stahl, and, looking at the matter in
the light of our present knowledge, it seems difficult to under-
stand how it was that the foremost chemist of the early years of
the eighteenth century, who busied himself especially with the
nature of combustion and with the theory of phlogiston, did not
put forward some striking chemical theory of breathing. That
he did not do so seems to have been due to the way in which
his mind was influenced by views which he had adopted con-
cerning the physical and mechanical effects of the flow of blood
through the capillaries.

Stahl taught that the most important fact about the
circulation of the blood was the passage through the capillaries,
the " transpression of the blood through the spongy, porous and
" exceedingly soft tissues of the body, by which doubtless it is
**kept constantly in a proper state of fluidity so that it may

LBCT. ix] Modern Doctrines of Respiration. 225

" remain not only suited for its perpetual circuit but also fitted
" for the due separation during that very circuit of the matters
" which have to be discharged from its midst."

He insisted that two things have to be borne in mind in
relation to this " transpulsion through the soft porous tissues.
" The first is the business of the vital tonic movement, which
"takes place and is developed in an independent manner,
"quite apart from our will and consciousness. By means of
" this the porous structures at one time being more constricted
" and compact, admit the blood more sparingly, and at another
" time being relaxed, give place to a readier and fuller passage."
This idea of the varying tonicity, of the varying tonic move-
ment, of the tissues was made by Stahl the comer-stone of
much of his pathology, and exerted a powerful influence over
medical thought for many years.

The second thing on which Stahl insisted as a result of the
* transpulsion ' is the warming of the blood. '* The second point
" to be noticed is the heating of the blood under, nay rather, on
"account of this same movement of the circulation at once
" pulsatory and tonic, and of the special intensity of each of
"these two kinds of movement." The heating he says is
simply the mechanical effect of the friction developed during
the passage. "Here again we ought to bear in mind the
"purely mechanical nature of the whole action. That is to
"say, this heating does not depend on any foreign particular
" kind of matter (except alone the special chemical constitution
" of the blood itself), but solely and simply on the movement
" and on its greater or less intensity, the variations of which
" are dependent on the one hand on the impetus itself of the
" impulse, and on the other hand on the tonic rigidity of the
" tissues according as these are constricted or relaxed."

Stahl thus deliberately rejects the view that the heat of
the blood and so of the body is due to chemical action ; he
regards it as solely and simply a mechanical effect. And this
conception of the origin of animal heat determined his view of
the function of breathing. According to him, the purpose of
the movements of the chest and of the lungs is to regulate
and facilitate the passage of the blood through the pulmonary
p. L. 15

226 The Rise of the Modern [lect.

blood vessels, and he discusses at length how the rhythmic
movement, the alternate expansion and contraction of the chest
affects the condition of blood vessels in the lungs, and so the flow
through them. And he takes credit to himself for being the first
to shew that so far from breathing having a cooling effect on the
blood, the friction engendered by the passage of blood through
the lungs is one of the chief sources of the heat of the body.

Thus the great chemist of the day was, by the influence of
a theory, led away from the true solution of one of the most
conspicuous chemical problems of physiology. And this was
the case, although he had put his foot on the right path.
Discussing the uses of air, he dwells briefly on the question
whether something may not in inspiration be given up to the
blood, just as in expiration there is, as he admits, a "transpiration
of aquosity in the form of vapour"; but he concludes that any
such entrance is of little moment ; and he sums up as follows.

" As however it is quite evident that air thus takes part in
"and contributes to this whole business of breathing in no
" other than a formal manner, as the phrase is '* (that is in a
mechanical manner), " so, as to whether, where and how it may
" seem to add something in the way of mere matter, we have
" already made a remark or two. Meanwhile it is wholly clear,
"from every point of view, that that something is neither
"great in quantity nor dense in quality, nor indeed anything
" different from the true nature of atmospheric air, which it
*' must necessarily be if breathing supplied any kind of spirit to
" the blood. If it be anything it must be something much more
** simple, namely a certain principle called phlogiston. Never-
" theless in respect even to this, doubts against it of no less
" weight than arguments in favour of it present themselves.
" For this principle does not abound in the air in sufficient
" quantity to be able at each breath to supply and add to the
" blood an amount of itself of any moment. This is a posteriori
" clear from the fact that only a very little of this matter of
"phlogiston can be received into even a large quantity of air,
"even in a place where it is sufficiently collected in it, as
" when inflammable things are burnt. However these things
"may be, these considerations, interesting perhaps to the

ix] Doctrines of Respiration. 227

" curious, add absolutely nothing to medical practice ; and it is
" not meet to waste any more time upon them."

Thus the great exponent of the chemistry of his time, and
especially of the chemistry of combustion, touched lightly the
key to one of the most important of the chemical problems of
the living body, and having touched it, deliberately drew his
hand away.

We naturally turn from Stahl to learn the views of the
other great chemist of the period, Hermann Boerhaave. We
must remember that the two were men of very unlike character.
Stahl was an investigator and an eager promulgator of new
views ; Boerhaave, though he did pursue with zeal and success
various experimental inquiries, was in the main an expositor
and an eclectic critic of the views of others. He put forward
no new theories of his own about breathing, and was content
to point out the conclusions which could be drawn from the
various results of other inquirers. In his great work on the
Elements of Chemistry , which deservedly became the text-book
of the age, after dwelling at some length on air and its properties
in a manner which shews his profound acquaintance with all
the researches of the time, he has a passage entitled " There is
" in air a wholly special virtue." In this, after shewing that all
living things stand in need of air, and after pointing out the
effect of air on the colour of blood, in turning dark blood scarlet,
he ends as follows.

" All these things prove that air possesses a certain occult
" virtue which cannot be explained by any of those properties of
" air which have hitherto been investigated. That in this virtue
*' the secret food of life lies hidden some chemists have asserted.
" But what it really is, how it acts and what it exactly brings
"about is still obscure. Happy the man who will discover
"it!"

We may recognize in this the sagacious observer groping
round the truth but unable to lay his finger exactly on it.
What were Boerhaave's more detailed teachings concerning
breathing may be inferred from the exposition given by
his illustrious pupil Haller; for Haller in the main followed
the lines of his great Master, differing from him chiefly in the

15—2

228 The Rise of the Modern [lect.

matters which were the subjects of his own original investi-
gations.

In his third volume, which is devoted to respiration, Haller
begins the subject with an account of the thorax and its
contents, and of the actions and uses of the various parts.
Then follows a discussion of the physical properties of air,
its weight and its * spring.* In the course of this he dwells on
the causes which destroy the 'spring' of air, noting as chief
among these the respiration of animals, and observing that
while this loss of 'spring' seems to be intimately connected
with the fact that animals cannot live in air which is not
renewed, the exact cause why they cannot do so is by no
means clear. Next, after an exposition of the general pheno-
mena and of the more mechanical problems of respiration, he
comes to the use of breathing and asks the question. Why
almost all animals stand in need of air? This leads to the
question, Whether air enters into and is mixed with the blood
in breathing? In respect to this he quotes three leading
opinions.

" From the most ancient times it has been a common view
" that as air is in nature the cause of almost all movement and
" without it fire cannot subsist or charcoal take fire, so also air
" enters into the vital humours of animals and provides in them
" that which brings about life. Very many are the authors who
" have approved of this view, among whom I will only mention
" the chief, and of these the more recent, who have maintained
" that the very air of the atmosphere itself, such as we take in
" by the mouth, reaches the blood. A diflferent opinion is held by
" those who have admitted that only a something reaches the
" blood from the air, which something some have spoken of as
" the more subtle particles or ether, others again as aereal nitre.
** A third party have maintained that the very air itself reaches
" the blood but air dissolved in water and deprived of its elastic
" force so that it cannot expand or undergo compression."

In discussing these several views Haller naturally dwells
upon the corresponding views held as to the use or function of
the air or part of the air thus reaching the blood. He speaks
of what may be called the physical hypothesis, such as that held

ix] Doctrines of Eespiration. 229

by Borelli, which taught that the air, still retaining its elasticity,
produced its effect on the blood in a physical manner, by exciting
vibrations for instance. He mentions the various forms of the
spiritual hypothesis, according to which either an actual vital
spirit, or some active particles, spirituous or ethereal, passed
from the air into the blood and gave it its vital properties. He
adds, ** Some indeed while refusing to admit in plain terms that
"any actual spirit is generated out of the air, nevertheless
" affirm that a vital entity of some kind is taken up from the
"air, and indeed men, wholly opposed to the vitalistic sect"
(referring to the passage of Boerhaave quoted above) "have
" not shrunk from this view." He next refers to the chemical
hypothesis, namely, that some chemical substance, a saline
vapour, or an acid volatile salt, or aereal nitre, passed from
the air into the blood and produced an effect on the blood
through chemical processes ; and he places the views of Mayow
on the same level as those of the many other chemical authors.

Discussing and rejecting all these various views, giving his
reasons for thinking that elastic air does not pass into the
blood, and refuting at some length the hypothesis that the
inspired air, through being cold, leads to a condensation of the
blood in the lungs, Haller warns the reader that the rejection
of all these views " does not lead to the conclusion that in
"breathing we derive nothing from the air."

He argues that since air exists in such quantity in all the
humours of the body and since a ready entrance of air is afforded
by the absorbing veinlets surrounding the pulmonary vesicles
full of air, air does enter the blood, but " in the lungs loses its
" elastic nature and so becomes readily soluble in water and
" vapour. Hippocrates counted air as a nutriment of the body,
"and since even the most solid parts of the body contain a
" great deal of air and give that up when they are dissolved
" and reduced to their elements, it is extremely probable that
"air plays the part of a cement holding together the earthy
" elements."

Such is Haller*s account of pulmonary inhalation, and he
completes the story by an account of pulmonary exhalation,
which he says consists chiefly of water but not mere water,

230 The Rise of the Modern [lect.

" water impregnated with a volatile fatty exhalation and not
"free from saline matter."

The subject of animal heat is so closely connected with
respiration that it will be convenient to note here what Haller
has to say about this. He expounds in the first place what
may be called the chemical theories of animal heat, the fer-
mentation in the heart, as put forward by van Helmont, and
the effervescence arising from the meeting of the old used-up
blood, spoken of as venous blood, and the fresh acid chyle, as
put forward by Sylvius. He merely touches in a very scanty
manner only on the more exact chemical view of Mayow. But
he goes on to say that "towards the close of the preceding
"(seventeenth) century greater attention was paid to the
"properties of solid parts, and the importance attached to
"chemical causes (such as van Helmont and Sylvius had
" brought to the front) somewhat fell oflf." Hence there came
into more general acceptance the physical view that the heat of
the body was due to the friction of the blood as it was driven
through the blood vessels, the view held as we have just seen
by Stahl.

Haller discusses all the various arguments for and against
these several views, and concludes as follows:

"So far then it seems most probable that the blood is
"certainly warmed by its movement, but it is by no means
" clear why it should be thus warmed to a higher degree than
"water would be under like circumstances, or why the tem-
"perature is never varied beyond certain narrow limits."

I have given this brief sketch of Haller's exposition in order
to shew how little advance has been made since the days of
the English School of which I spoke in a preceding lecture.
Perhaps one ought rather to say how things had gone back, for
the lead offered by Mayow as it had been rejected by those
coming between him and Haller, so it was rejected by Haller
himself.

Meanwhile the first step in the new progress which before
long was to be made had been taken, and that in Mayow's
country, in England, or rather in Great Britain.

Well known to Haller, though perhaps not fiilly appreciated

ix] Doctrines of Be^nration. 231

by him, were the works of Stephen Hales. This remarkable
man did not belong to the medical profession, was not the
holder of any medical chair. He was a clergyman, an active,
perhaps too active and zealous parish priest. Bom in 1677
at Bekesboume in Kent, educated at Corpus Christi College
in Cambridge, of which he was some time a Fellow, he
became perpetual curate or minister at Teddington on the
Thames, where he made the acquaintance of Horace Walpole,
who however speaks of him ' as a poor, good, primitive creature,*
of Pope and others. He was also Rector of Farringdon in
Hampshire. He died in 1761. Clergyman as he was, he was
devoted to science; he had begun to experiment while at
Cambridge " in the elaboratory of Trinity College " which the
then Master of Trinity, the great scholar Bentley, anxious to
make his College the seat of all kinds of learning, had estab-
lished ; and he continued his researches amid his parish duties
at Teddington. He was a sanitary pioneer, being the first to
introduce ventilation, an ardent advocate of temperance prin-
ciples, and one of the founders of a society which afterwards
became the present Society of Arts. The Royal Society, of
which he was an active Fellow, published his Statical Essays,
the first volume of which appeared in 1726, the second in 1732.
The second volume entitled Hcemastatics deals chiefly with the
mechanics of circulation. He was the first to determine, by
actual experiment on the living animal (he used the horse), the
pressure of blood on the blood vessels ; and the researches
recorded in this volume stand out conspicuous as marking
the chief advance made in this branch of physiology between
Borelli and Poisseuille. The first volume which treats chiefly
of the flow of sap in vegetables contains an essay with the
following title.

" A specimen of an attempt to analyse the air by a great
"variety of chymico-statical experiments which shew in how
"great a proportion air is wrought into the composition of
"animal, vegetable, and mineral substances, and withal how
"readily it assumes its former elastic state when, in the dis-
" solution of those substances it is disengaged from them."

He calls all gases ' air/ and recognizes air or gas as existing,

232 The Rise of the Modern [leot.

first in an elastic state, in which the particles repel each other,
and secondly in a reduced or fixed state, in which their particles
are attracted by the particles of some other substance, e,g.
sulphureous particles.

I refer to him not because he made any definite special
contribution to our knowledge of respiration (though his work
had a remarkable practical side through the introduction of
ventilation), but because his writings contain the first clear
enunciation of the existence of gases in a free and in a com-
bined condition. By clearly stating this principle he exercised
a notable influence on other men's researches, and thus power-
fully aided the discoveries which were made by others after him.
This is what he says :

"Since, then, air is found so manifestly to abound in almost
" all natural bodies ; since we find it so operative and active a
" principle in every chymical operation ; since its constituent
" parts are of so durable a nature, that the most violent action
" of fire or of fermentation cannot induce such an alteration of
" its texture as thereby to disqualify it from resuming either by
*'fire or fermentation its former elastick state; .... since
" then this is the case may we not with good reason adopt this
" now fixed, now volatile Proteus among the chymical principles,
" and that a very active one, as well as acid sulphur ? notwith-
" standing it has hitherto been overlooked and rejected by
"chymists, as in no way entitled to that denomination."

Hales, it will be observed, speaks of air (or gas) as if it were
always the same thing. He knew that air had not always the
same properties, that sometimes it was inflammable and some-
times not, sometimes good for breathing, sometimes not, but
these were instances of varying qualities of the same thing, not
of different things. He ignored van Helmont's discovery of a
gas which was a different thing from air. But the avatar of
the now nearly forgotten van Helmont was soon to come.

In 1754 there appeared a Dissertatio de humor e addo a
cibo orto et de magnesia by one Joseph Black, who, born at
Bordeaux in 1728, had been educated at Belfast, Glasgow,
and Edinburgh, and who in the year following the appearance
of his dissertation was appointed Professor of Chemistry at

ix] Doctrines of Jiespiration. 233

Glasgow in succession to Cullen.* Ten years later he became,
again in succession to CuUen, Professor of Chemistry at
Edinburgh, where he died in 1799. The Latin dissertation of
1754 appeared in the following year as an English essay,
entitled, "Experiments on Magnesia Alba, Quick-lime, and
other Alkaline Substances."

Stone in the bladder and gravel in the urine were in those
days attracting much attention in the medical profession, and
the qualities of various alkaline bodies proposed as remedies for
them were being much discussed.

According to prevalent ideas, governed by the phlogiston
theory of Stahl, lime or chalk became quicklime, became
caustic by taking up phlogiston, and when slacked gave out
phlogiston; that is to say lime suffered gain in becoming
caustic quick-lime, and caustic quick-lime suffered loss in being
slacked and becoming mild.

Black made the notable observation that ordinary or mild
lime lost in weight when it was burnt into caustic lime. He
further observed that all ' mild ' alkalis, lime, magnesia, and
the like, when treated with acids, gave off a particular kind of
gas or air. When caustic lime by exposure to the air became
miW lime, the change, he argued, consisted in the lime taking
up from the atmosphere this particular kind of air. *' Quick -
" lime therefore does not attract air when in its most ordinary
" form, but is capable of being joined to one particular species
" only, which is dispersed through the atmosphere either in the
" shape of an exceedingly subtle powder, or more probably in
" that of an elastic fluid. To this I have given the name of
'''fixed airy

Moreover when mild lime was burned and so became caustic
lime, this same fixed air was given off. It was the loss of this
fixed air which accounted for the loss of weight when mild
lime was burned into quick-lime. In fact the mild alkalis
were compounds of caustic alkalis with fixed air.

This discovery of Black really entailed the destruction of
the phlogiston theory, but that theory had established itself in
the minds of men of the time far too firmly to be driven off at
the first assault.

234 The Rise of the Modem [lbct.

Black moreover made another discovery. Using as a test
for the presence of fixed air the feet that it, when driven
through a clear solution of lime water, %,e. a solution of caustic
lime, caused a precipitation, in consequence of its combining
with the caustic lime and converting it into mild lime, he was
able to prove that fixed air was given off in fermentation, was
a product of the burning of charcoal and was present in ex-
pired air.

He thus rediscovered the gas which van Helmont had
discovered more than a hundred years ago. This is what
he says, writing some years afterwards in his Treatise of
Chemistry :

" I fully intended to make this air (fixed air) the subject of
"serious study.... In the same year, however, in which my first
" account of these experiments (on magnesia, etc.) was published,
" namely 1757 (sic), I had discovered that this particular kind of
" air, attracted by alkaline substances, is deadly to all animals
*' that breathe it by the mouth and nostrils together ; but that
" if the nostrils were kept shut I was led to think that it might
"be breathed with safety. I found for example that when
" sparrows died in it in ten or eleven seconds, they would live
"in it for three or four minutes when the nostrils were shut
"by melted suet. And I convinced myself that the change
" produced on wholesome air by breathing it, consisted chiefly,
"if not solely, in the conversion of part of it into fixed air.
" For I found, that by blowing through a pipe into lime water,
" or a solution of caustic alkali, the lime was precipitated, and
"the alkali was rendered mild. I was partly led to these
" experiments by some observations of Dr Hales, in which he
" says, that breathing through diaphragms of cloth dipped in
" alkaline solution made the air last longer for the purposes of
" life.

" In the same year I found that fixed air is the chief part
" of the elastic matter which is formed in liquids in the vinous
** fermentation. Van Helmont had indeed said this, and it was
"to this that he first gave the name gas silvestre. It could
" not long be unknown to those occupied in brewing or making
"wines. But it was at random that he said it was the same

ix] Doctrines of Respiration. 235

" with that of the Grotto del Cane in Italy (but he supposed
" the identity, because both are deadly), for he had examined
** neither of them chemically, nor did he know that it was the
"air disengaged in the effervescence of alkaline substances
"with acids. I convinced myself of the fact by going to a
"brewhouse with two phials, one filled with distilled water,
"and the other with lime water. I emptied the first into a
"vat of wort fermenting briskly, holding the mouth of the
"phial close to the surface of the wort. I then poured some
" of the lime water into it, shut it with my finger, and shook it.
" The lime water became turbid immediately.

"Van Helmont says that the dunste or deadly vapour of
" burning charcoal is the same gas silvestre ; but this was also
"a random conjecture. He does not even say that it ex-
**tinguishes flame; yet this was known to the chemists of
"his day. I had now the certain means of deciding the
"question, since, if the same, it must be fixed air. I made
"several indistinct experiments as soon as the conjecture
"occurred to my thoughts; but they were with little con-
"trivance or accuracy. In the evening of the same day that
"I discovered that it was fixed air that escaped from fer-
" men ting liquors I made an experiment which satisfied me.
" Unfixing the muzzle of a pair of chamber bellows, I put a
"bit of charcoal, just red-hot, into the wide end of it, and then
"quickly putting it into its place again, I plunged the pipe to
" the bottom of a phial, and forced the air very slowly through
"the charcoal, so as to maintain its combustion, but not
"produce a heat too suddenly for the phial to bear. When
" I judged that the air of the phial was completely vitiated,
" I poured lime water into it, and had the pleasure of seeing it
" become milky in a moment.

"I now admired van Helmont's sagacity, or his fortunate
"conjecture; and, for some years, I took it for granted that
" all those vapours which extinguish flame, and are destructive
" of animal life, without irritating the lungs or giving warning
" by their converse nature are the gas silvestre of van Helmont
" or fixed air."

It is thus evident that Black so early as 1757, the year

236 The Rise of the Modem [lbct.

Haller published the first volume of his Eleinenta, had redis-
covered the gas sylvestre of van Helmont, and to a certain
extent learned its nature. He recognised it as a distinct gas,
as something which, though it might be present in atmospheric
air, was distinct from air, was not a mere modification of air.
He saw that it was irrespirable ; and though he did not lay hold
of its nature with sufficient distinctness to justify his calling it
by the name applied to it much later and now used by us, the
name of carbonic acid gas, he proved by experiment that it arose
from burning charcoal.

Black recognized this fixed air as being present in ordinary
air, but he nowhere states to what extent it is so present. It
was as we have seen recognized by Mayow, by Haller, and
indeed generally that part only of the atmosphere was useful
for respiration. Mayow as we have also seen recognized this
respirable part as distinct fi"om the rest of the atmosphere ; the
others were not so clear, but in any case in the course of the
century the words respirable air came into use. Black seems,
and that very naturally, to have thought at first that the part
of the atmosphere which was not respirable was his * fixed air * ;
but he was led by a countryman of his to see that part of the
atmosphere though not respirable was something quite diflferent
from his fixed air. He says in his Treatise on Chemistry :

^ This portion of our atmosphere (the irrespirable portion,
" that which the Swedish chemist, Scheele had called foul air),
"was first discovered in 1772 by my colleague Dr Jlutherford
" and published by him in his inaugural dissertation. He had
" then discovered that we were mistaken in supposing that all
"noxious air was the fixed air which I had discovered. He
"says that after this has been removed by caustic alkali or
"lime, a very large proportion of the air remains which ex-
"tinguishes life and flame in an instant."

We may therefore say that nitrogen was discovered by
Rutherford in 1772 ; but he did not give it this name, nor was
he aware that this irrespirable constituent of the atmosphere
had anything to do with the famous nitre which had so much
occupied the minds of philosophers of the preceding century.
It was not indeed until Cavendish, that eccentric nobleman.

ix] Doctrines of Respiration. 237

acute and careful observer, skilful experimenter, but strange
being, obtained nitric acid from the atmosphere by electric
sparking, that the connection between nitre and the chief
constituent of the atmosphere became known. It was this
connection which led the French chemist Chaptal to suggest
for the atmospheric constituent the name nitrogen ; but it was
Lavoisier who first clearly defined its characters, and he always
preferred to call it by a name which indicated its inability to
sustain life, azotic gas or azote.

We have said that Black rediscovered under the title of
fixed air the carbonic dioxide which van Helmont had dis-
covered as gas sylvestre. We may similarly say that Priestley
and Lavoisier rediscovered the gas which Mayow had made
known by the name of igneo-aereal salt or spirit.

I need not here dwell at any length on the life of Joseph
Priestley. Born in 1733 at Fieldhead near Leeds, in Yorkshire,
educated to be a minister in the Unitarian Church, at first a
somewhat " stickit " minister in Suffolk and in Cheshire, after-
wards holding a more congenial post as tutor in the academy
at Warrington, for some time literary companion to Lord
Shelbume, his most active life was spent as minister first at
Leeds, then at Birmingham. Man of letters as well as man of
science, prolific theologian and ardent politician, his views did
not commend themselves to the people, or shall I rather say to
the populace ; as is well known he had to flee from Birmingham,
and after hiding somewhile in London passed over to America
and took up his abode at Northumberland in Pennsylvania,
where in 1804 he died.

Priestley's first work on respiration consisted in attempts to
restore, to render once more respirable, air which had been
vitiated, rendered irrespirable by being breathed. After several
failures he at last succeeded by means of vegetation. He says :

" I have been so happy as by accident to have hit upon a

" method of restoring air which has been injured by the burning

" of candles, and to have discovered at least one of the restora-

" tives which nature employs for this purpose. It is vegetation,

* ******

"One might have imagined that, since common air is

238 The Rise of the Modem [lect.

** necessary to vegetable as well as to animal life, both plants
" and animals had affected it in the same manner, and I own I
" had that expectation, when I first put a sprig of mint into a
" glass jar, standing inverted in a vessel of water : but when it
'* had continued growing there for some months, I found that
" the air would neither extinguish a candle, nor was it at all
" inconvenient to a mouse which I put into it. The plant was
" not affected any otherwise than was the necessary consequence
" of its confined situation.

♦ *««♦♦*

" Finding that candies would bum very well in air in which
" plants had grown a long time, and having had some reason to
"think that there was something attending vegetation which
"restored air that had been injured by respiration, I thought it
" was possible that the same process might also restore the air
" which had been injured by the burning of candles.

''Accordingly on the 17th of August, 1771, 1 put a sprig of
" mint into a quantity of air, in which a wax candle had burnt
" out, and found that on the 27th of that same month another
" candle burned perfectly well in it. This experiment I repeated,
" without the least variation in the event, not less than eight
" or ten times in the remainder of the summer.

" This restoration of air, I found, depended on the vegetating
" state of the plant ; for though I kept a great number of the
" fresh leaves of mint in a small quantity of air in which candles
*' had burnt out, and changed them frequently, for a long space
" of time, I could perceive no melioration in the state of the air."

About the same time, following up an experiment of Hales,
he prepared what he called nitrous air or nitrous acid, and he
made the remarkable observation that this nitrous acid in
producing certain effects on air acted only on air fit for
respiration. He says :

*' One of the most conspicuous properties of this kind of air
" is the great diminution of any quantity of common air with
** which it is mixed, attended with a turbid red, or deep orange
" colour and also a considerable heat.

ix] Doctrines of Hespiration. 239

"I hardly know any experiment that is more adapted to
" amaze and surprise than this is, which exhibits a quantity of
" air, which, as it were, devours a quantity of another kind of
" air, half as large as itself, and yet is so far from gaining any
" addition to its bulk, that it is considerably diminished by it."

He found this nitrous air could be conveniently used as
a test of the fitness of air for breathing. Either of these lines
of inquiry might have led him to the discovery which he
afterwards made. But they did not. His mind was too full of
phlogiston, and under the idea that common air consisted of
acid gas and phlogiston, he pursued long inquiries into other
acid gases than the nitrous air, into marine acid air, vitriolic
acid air, and even vegetable or acetous acid air.

These inquiries did not lead far ; but another independent
inquiry suddenly brought him, accidentally as it were, upon his
great discovery.

He obtained after some difficulty an adequate burning-glass
such as would enable him to raise to the requisite heat bodies
enclosed in a glass vessel, the gases developed in which he could
study with success. By the help of this burning-glass he,
following up Hales' views, ** tried to find out what kind of air a
" great variety of substances natural and artificial would yield."

While engaged on this inquiry, which was quite independent
of his earlier researches, he found that mercuric oxide, mercurius
calcinatus per se, yielded under the action of the sun's rays a
quantity of gas which was not inflammable, and which so far
from quenching flame was exceedingly favourable for com-
bustion. These are his words:

" With this apparatus, after a variety of other experiments,
** an account of which will be found in its proper place, on the
" 1st August, 1774, 1 endeavoured to extract air from mercurius
" calcinatus per se ; and I presently Found that, by means of this
" lens, air was expelled from it very readily. Having got about
''three or four times as much as the bulk of my materials, I
" admitted water to it, and found that it was not imbibed by it.
" But what surprised me more than I can yet well express, was
" that a candle burned in this air with a remarkably vigorous
" flame, very much like that of the enlarged flame with which a

240 The Rise of the Modem [lect.

" candle bums in nitrous air, exposed to iron or liver of sulphur ;
" but as I had got nothing like this remarkable appearance from
" any kind of air besides this particular modification of nitrous
" air, and I knew no nitrous acid was used in the preparation of
" mercurius caldnatus, I was utterly at a loss how to account for
"it."

He further mentions that " the flame of the candle besides
" being larger, burned with more splendour and heat than in that
" species of nitrous air ; and a piece of red-hot wood sparkled in
"it."

He obtained the same gas from red precipitate and from
nimium ; he found that a mouse lived well in it, and on trying
it with his nitrous air he found that it was much better than,
four or five times as good as common air. It was therefore not
common air, it was the same thing as that which renders
common air fit for respiration, but as it were in a more con-
densed form.

Priestley as I have said was devoted to the phlogiston
theory. He thought phlogiston ; he could not lay hold of any
subject save from the phlogiston point of view. Air supported
combustion because it took up the phlogiston given out by the
burning body. Common air was to a certain extent free from
phlogiston, it was dephlogisticated, and in proportion as it was
so dephlogisticated, it could support combustion. Common air
supported combustion to a certain extent only, a part only of it
could support combustion because it was only partially dephlo-
gisticated. The new air which he got from the metallic oxides
was wholly dephlogisticated.

" I got air," says he, " which I was gradually satisfied had
"all the properties of common air, only in much greater
" perfection, so as to be entitled (according to my idea of purity
" or impurity with respect to air) to the name of dephlogisticated
" air, which for that reason I gave to it."

He recognized the new thing which he had got not as a new
thing, a new gas or air, different from the rest of the atmosphere,
but as a part of the atmosphere brought into a new condition.

He thus in 1774 prepared oxygen, he prepared the igneo-
aereal substance of Mayow, but he did not discover it, in the

ix] Doctrines of Respiration. 241

sense that he did not discover the true nature of the substance
which he had prepared ; what he did discover was that the air
which he had prepared was that part of common air which sup-
ported combustion and life.

By the help of this discovery he could now explain on the
phlogiston theory his previous results.

Animals whose bodies abound in phlogiston, introduced by
their food (for both the dead food and the body which eats the
food are combustible, and combustible means holding phlogiston),
in the act of breathing give out phlogiston so long as the
atmosphere they breathe contains enough dephlogisticated air
to absorb the phlogiston ; when this dephlogisticated air becomes
saturated with phlogiston and can receive no more, the atmo-
sphere ceases to be respirable.

Animals can take in, can imbibe phlogiston only as part
of their food, can take it in only when it is already combined
with the substance of their food. Plants, on the other hand,
under the influence of light can imbibe phlogiston directly from
the air, can withdraw phlogiston from and so dephlogisticate the
air ; hence it is that they can render respirable or dephlogisticated
the air which animals have rendered irrespirable or phlogisti-
cated. But they can do this only under the influence of light.

" In these experiments," his experiments on air, " it clearly
" appeared that respiration is a phlogistic process aflfecting air
" in the very same manner as every other phlogistic process (viz.,
"putrefaction, the effervescence of iron-filings and brimstone,
" or the calcination of metals, &c.) aflfects it ; diminishing the
"quantity of it in a certain proportion, lessening its specific
" gravity, and rendering it unfit for respiration or inflammation,
" but leaving it in a state capable of being restored to a tolerable
" degree of purity by agitation in water, &c.'*

The last words in the above sentence refer to some earlier
experiments made before he had observed the restoration of
vitiated air by vegetation, experiments which led him to think
that he could obtain a certain amount of restoration by mere
agitation with water.

He many times insists that respiration and putrefaction are
the same things.

p. L. 16

242 The Rise of the Modern [lect.

" Respiration and putrefaction affect common air in the same
" manner, and in the same manner in which all noxious processes
'' diminish air and make it noxious, and which agree in nothing
" but the emission of phlogiston. If this be the case it should
" seem that the phlogiston which we take in with our aliment,
" after having discharged its proper function in the animal system
"(by which it probably undergoes some unknown alteration)
*'i8 discharged as effete by the lungs into the great common
'* menstruum, the atmosphere."

He saw, moreover, in the changes of the colour of blood
a confirmation of his views. Venous blood he took to be
blood laden with phlogiston; this reaching the lungs parted
with its phlogiston to the dephlogisticated part of the inspired
air in the lungs, and went on its way as dephlogisticated blood
to gather up phlogiston once more as it coursed through the
body. A proof of this view he saw in the fact that blood
exposed to dephlogisticated air gave up its phlogiston and
became bright arterial dephlogisticated blood. Arterial blood
exposed to phlogisticated air became phlogisticated, dark, and
venous.

" Having taken the blood of a sheep I introduced pieces

"of the crassamentum, contained in nets of open gauze,
" sometimes through water, and sometimes through quicksilver,
" into different kinds of air, and always found that the blackest
" part assumed a florid red colour in common air, and more espe-
" cially in dephlogisticated air, which is purer and more fit for
" respiration than common air (and accordingly the blood always
" acquired a more florid colour, and the change was produced
" in less time in this than in common air); whereas the brightest
" red blood became presently black in any kind of air that was
" unfit for respiration, as in fixed air, inflammable air, nitrous
"air or phlogisticated air; and after having become black in
*' the last of these kinds of air, it regained its red colour upon
" being again exposed to common air or to dephlogisticated air ;
" the same pieces becoming alternately black and red, by being
"transferred from phlogisticated to dephlogisticated air; and
*'vice versd.

" In these experiments the blood must have parted with its

ix] Doctrines of Respiration. 243

" phlogiston to the common air or dephlogisticated air, and have
" imbibed it and have become saturated with it when exposed
"to phlogisticated, nitrous, inflammable, or fixed air."

It will be observed that Priestley's idea of respiration as
being simply the phlogistication of dephlogisticated air left no
room for any other product of respiration. Black, we have seen,
had clearly shewn that his fixed air was a product of respira-
tion, was a constituent of expired air. Priestley (and this shews
how far he was from laying hold of the real truth about respira-
tion) had to explain away in some manner or other Black's fixed
air. He attempts to shew that it does not come from the lungs.

" It now being pretty clearly determined that common air
"is made to deposit the fixed air which entered into the
"constitution of it by means of phlogiston in all cases of
" diminished air, it will follow that in the precipitation of lime
" by breathing into lime water the fixed air, which incorporates
" with lime, comes not from the lungs, but from the common
"air, decomposed by the phlogiston exhaled from them, and
" discharged, after having been taken in with the aliment, and
"having performed its function in the animal system."

Priestley's story is a striking example of the influence of a
dominant theory. He was, as we have said, steeped in the
phlogiston theory ; he clung to it to the end of his life, though
to others it seemed before that to have received its death-blow.
From what I have said it is clear that he had formed in his
mind an image of the respiratory process which, so far as
oxygen is concerned, we with our present knowledge may call
wonderfully exact, save that it was, in a sense, completely
upside down, an image of the truth, but an inverted image.
Where we say * took,' he said ' give,' and vice versd, and this so
persistently throughout the whole business that anyone who at-
tempts, as I have just done, to describe respiration in Priestley's
terms, will find that he has to be very careful at each step lest
he represent him as saying exactly the opposite of what he did
say. It is so difficult for us, as it was so easy for him, to think
of oxidation as a ' giving up,' and not as a * taking in.'

Meanwhile another mind of quite a diflferent mould was
laying hold of the truth in its proper, erect position. Priestley

16—2

244 The Rise of the Modem [lect,

was it is true a philosopher, a real investigator of nature, but
he was also, and even more so, a politician and a theologian.
In this latter side of his life the mode of thinking which he
naturally adopted led him to regard every new fact which came
before him as confirming the views at which he had already
arrived, and perhaps especially encouraged him to expound the
new fact as affording such welcome confirmation. Possibly it
was this other side of his mental activity which led him to cling
so closely to the phlogiston faith. Indeed when we compare
his character with that of Stahl, the founder of the phlogiston
theory, we may see a certain likeness between the two.

The man who if he was not the first to prepare, was at least
the first to discover oxygen, was free from all such tendencies
to cling to old opinions. He was wholly and entirely the man
of science holding to an old view only until the new one is
ready, always prepared, at the bidding of a new indubitable
fsM5t, to throw aside at once his most cherished ideas.

I need not dwell long on the personal history, the private
life of Antoine Laurent Lavoisier, and indeed there is little to
tell save the tragic end of it.

Bom on Aug. 26, 1743, he was educated at the CoUfege
Mazarin. Here, though intended for the law, he was early
drawn into studies of natural science ; and to these he quietly
devoted the rest of his life, spending his days, save those
which he had to give up to official duties in connection with
Le Ferme G^n^ral which he early took upon himself, in the
researches of which I am about to speak, and in others which
lie outside my present task. In 1768, at the early age of
twenty-five, he was admitted into the Academy of Sciences,
to which body he from time to time made known the brilliant
results of his labours.

In 1775, the year after Priestley had prepared his dephlogis-
ticated air, Lavoisier published the immortal paper "On the
"nature of the principle which combines with metals during
** their calcination." He saw the facts which Priestley had seen,
but saw them eye to eye, saw them without the veil of precon-
ceived ideas. The metallic oxide when it became a metal did not
take up phlogiston from the air, but gave up something to the

ix] Doctrines of Respiration. 245

air. The metal when it was burnt into the oxide did not
give up phlogiston to the air, it took something from the air.
The metallic oxide in becoming metal, instead of gaining lost
in weight. The metal in becoming metallic oxide, instead of
losing gained in weight. Objections to the phlogiston theory
based on questions of weight had been urged before, but the
theory had swept them away. Now they were put in such a
way that they swept away the theory. Smitten with these
experiments the scientific Dagon, the image before which men
had bowed their knees for a hundred years, fell crumbling to
the ground.

Men will tell you tales of how Priestley on a visit to Paris
in the late autumn or winter of 1774, chatted freely to his
scientific brethren about the experiment which he had just made
with his mercuric oxide and his burning-glass; and they will
assert that Lavoisier was thus led to his pregnant result.
Whether this be true or no does not seem to me to be of vital
importance; whether Lavoisier got at his result wholly of
himself or no, he and he alone, not Priestley in any way, got at
the true meaning of the result. He and he alone really
discovered oxygen.

Two years later, in 1777, the year of Haller's death, in a
paper entitled * General Considerations concerning the Nature of
Acids and on the Principles of which they are composed,' he
brought forward abundant proofs that the principle which
combines with metals when they are calcined, the dephlogisti-
cated air of Priestley, is the constitutive principle of acidity.

"I shall therefore designate dephlogisticated air, air emi-
" nently respirable, when in a state of combination or fixedness
" by the name of ' acidifying principle,* or, if one prefers the same
** meaning in a Greek dress, by that of * oxygine ' principle."

In the same year 1777.. he attacked the problem of animal
respiration in a paper, "Experiments on the Respiration of
"Animals and on the Changes which the Air undergoes in
"passing through the lungs."

Upon the discovery of oxygen and of the true nature of
oxidation Priestley's image of the respiratory process forthwith
inverted itself. It was seen at once that respiration was
oxidation, that air which had been respired resembled air in

246 The Rise of the Modem [lect.

which a metal had been calcined in so far that it had lost a
certain quantity of its oxygen.

But Lavoisier went further than this, he saw that there was
an essential difference between air in which a metal had been
calcined and air which had been breathed. The latter con-
tained what the former did not, Black's fixed air, for it
precipitated lime water. Lavoisier, unlike Priestley, with no
veil before his eyes, saw no reason to doubt that this fixed air
came from the lungs; and he recognized accordingly that in
respiration there were two factors, the disappearance of oxygen
and the appearance of fixed air.

He took a measured quantity, 12 inches of vitiated air, of
air which had been breathed, and passed it over caustic alkali.
It was diminished in volume by Jth, and the caustic alkali was
found to have lost its causticity, and when treated with acid to
give off fixed air. Lavoisier found that Black's fixed air could
be most readily prepared by treating chalk with acids, and he
had determined that it gave an acid reaction; hence he pre-
ferred to call it aeriform calcic acid. Hence he states the
conclusion to be derived from the experiment just quoted in the
following terms. " Air vitiated by breathing contains ^th part
" of an aeriform acid like that which is obtained from chalk."

After this aeriform acid has been removed the air becomes
exactly like the air in which a metal has been calcineci, it is
an air which extinguishes flame and is unfit for being breathed.
This residual air since it would not support life Lavoisier
proposed to call azotic air or azote. When this azote was
mixed, to the extent of Jth its volume, with air eminently
respirable, dephlogisticated air (he did not as yet feel justified
in using largely his new term oxygine), it became exactly like
common air, the air of the atmosphere.

He draws from his experiments the following physiological
conclusion :

"Either the portion of the air eminently respirable con-
" tained in the air of the atmosphere is converted into aeriform
"calcic acid, or a change is effected in the lung by which on
" the one hand the air eminently respirable is absorbed, and on
"the other hand the lung substitutes in its place in nearly
"equal volume a portion of aeriform calcic acid. I shewed

ix] Doctrines of Respiration. 247

"during Easter 1775 that air eminently respirable could be
" entirely converted into aeriform calcic acid by the power of
"charcoal, and in other memoirs I shewed the same fact by
"other means" (that is to say, he had proved that Black's
fixed air was a compound of carbon and oxygen). " This makes
" the former of the two views possible. On the other hand it
"is also possible that the air eminently respirable combines
"with the blood. We know that it is a property of the air
"eminently respirable to communicate a red colour to the
" bodies with which it combines, especially metallic substances,
" as, for example, mercury, lead, and iron. May we not conclude
" that the red colour of blood is due to a combination of the air
"eminently respirable, or more exactly, as I shall shew in a
" memoir shortly to appear, to the combination of the base of
"the air eminently respirable with an animal liquid, in the
" same way that the red colour of red mercury precipitate and
" nimium is due to a combination of the base of the same air
"with a metallic substance? For Priestley has shewn that
" blood becomes red when exposed to air eminently respirable,
" and dark when exposed to aeriform calcic acid ; in the latter
"case becoming red again when exposed once more to air
" eminently respirable.

" We may therefore regard as proved,

"1. Respiration affects only the air eminently respirable;
" the rest of the atmosphere, the mephitic part," the part which
he later called azote, " remains unchanged.

" 2. The calcination of metals in atmospheric air goes on
" until the air eminently respirable contained in the atmosphere
"is exhausted and combined with the metal, but will not go
"on afterwards.

"3. Animals shut up in a confined atmosphere succumb,
"so soon as they have absorbed or converted into aeriform
"calcic acid the greater part of the respirable portion of the
"atmosphere, leaving a remainder.

" 4. This remainder is the same in calcination and in respi-
" ration, provided that in the latter case the aeriform calcic
"acid be removed; and in any case is reconverted into
"ordinary atmospheric air by adding to it air eminently
" respirable.

248 The Rise of the Modern [lect.

" If we augment or diminish in any atmosphere the quantity
"of air eminently respirable, we augment or diminish the
" quantity of metal which can be calcined in it, and to a certain
" extent the time during which the animal can live in it."

Thus at a single stroke as it were did this clear-sighted
inquirer solve the problem of oxidation, and almost, if not
quite, the problem of respiration. He brought our knowledge
of the latter process very nearly to its present condition.

Yet he went still a step further.

Three years later, in 1780, he and the great mathematician
Laplace published their celebrated memoir on heat.

In this memoir these authors, after placing the theory of
the heat of oxidation and combustion on a sound basis, after
describing their methods for determining the heat given out
during chemical action, the results which they obtained, and
the conclusions to be derived from those results, applied their
new views to elucidate the cause of the natural heat of living
bodies.

As we have seen, Haller left the problem of animal heat in
an unsettled condition. The chemical theories of its origin had
fallen somewhat into disrepute; but the mechanical theory,
that it was due to the friction of the blood in its movements,
though favoured by Haller did not seem to him to be wholly
satisfactory.

Black, besides discovering fixed air, had prepared the way
for the true theory of heat by pointing out the distinction
between latent and sensible heat, and had introduced the ideas
of capacity for heat and of specific heat. In 1777-9 Adair
Crawford published a theory of heat, based on Black s views ;
a theory which, as he put it forward, seems vague and hypo-
thetical, but which at least has the merit of connecting animal
heat and respiration in a way which had not been done before.
His theory was as follows :

Inspired air contains elementary fire, and meets in the lungs
with the inflammable principle present in the blood. The
elementary fire leaves the air of the lungs to join the blood,
the capacity for heat of which is increased. In the course of
the circulation the blood again becomes impregnated with the
inflammable principle by which the capacity of the blood for

ix] Doctrines of Respiration. 249

heat is diminished. It accordingly gives up heat to the tissues.
Thus in the lungs the blood discharges inflammable principle
and absorbs heat, in the system it imbibes this principle and
emits heat.

It must be remembered that Black and Crawford, and
indeed Lavoisier, regarded heat or caloric not, as we now do, as
a form of energy, but as a thing or substance which combined
with the thing heated, a something which was the physical
analogue of the chemical phlogiston.

Very different from Crawford's loose hypothesis is Lavoisier s
clear and succinct statement of the results of his and Laplace's
experiments. Having ascertained the amount of heat given out
by the combustion of a given weight of carbon into what now
began to be called Dot aeriform calcic acid but carbonic acid gas,
so quickly did knowledge advance in these few pregnant years,
and having determined on the one hand how much carbonic
acid was given out by, that is to say how much carbon under-
went combustion in the body of an animal during a given time,
and on the other hand how much heat was given out by the
animal during the same time, the authors found on comparing
the results, that the heat given out by the animal was about
the same as that given out by a quantity of carbon oxidized
so as to produce the amount of carbonic acid gas expired by
the animal during the time.

They thus felt justified in stating the following conclusion.
"Respiration is therefore a combustion, slow it is true, but
" otherwise perfectly similar to the combustion of charcoal. It
" takes place in the interior of the lung without giving rise to
"sensible light because the matter of the fire (the caloric) as
" soon as it is set free, is forthwith absorbed by the humidity
"of these organs. The heat developed by this combustion is
"communicated to the blood which is traversing the lungs,
"and from the lungs is distributed over the whole animal
" system."

A few years later, in 1785, Lavoisier was led to recognize
that he had been in error in supposing that respiration was a
combustion of carbon only. In a memoir entitled " The Changes
undergone by Respired Air," he made a careful quantitative
estimation of the quantity of oxygen (or ' vital air,' as he still

250 The Rise of the Modem [lect.

preferred to call it, being unlike some other makers of new
terms chary of using his new word, oxygine) which disappeared
when an animal was made to breathe a measured atmosphere of
it for a given time. He also estimated the quantity of carbonic
acid gas given out during the same time ; and knowing by this
time the exact composition of carbonic acid, knowing how much
oxygen was present in a given quantity of carbonic acid, he found
that all the oxygen which disappeared did not reappear in the
carbonic acid respired. Some of the oxygen was used for
something else than the combustion of carbon and the pro-
duction of carbonic acid.

Now in expired air there was nothing present in measurable
quantity except carbonic acid and the substance known as water.

Here I must go back a little.

Van Helmont found that his gas, of which, as seen in gas
sylvestre, the conspicuous feature was that it would not support
burning, though sometimes uninflammable, sometimes caught
fire and burnt. Boyle in 1672 recognized that the air or gas given
oflF when metals were dissolved in acids was inflammable. And
during the eighteenth century mention is from time to time made
of factitious air, and of this air being often inflammable. Hales
refers to it ; and Haller speaks of factitious air, such as is produced
by the action of acids on metals, and is frequently inflammable,
as being unfit for respiration, although it is elastic. As we have
seen, Haller attributed much importance in respiration to the
fact that air in being breathed lost its elastic power, and
thought the possession of elastic power a feature of respirable
air; hence he found a difficulty in elastic factitious air not
being respirable.

It is with Cavendish however, and his experiments
on factitious air in 1766, that our real, exact knowledge of
inflammable factitious air begins; and when in 1781 he dis-
covered the composition of water, this mysterious gas became
henceforth known as hydrogen. It was the last of the four
chief physiological gases to be run to earth. As we have seen,
carbonic acid gas first laid hold of van Helmont in 1640
or thereabouts, was more firmly grasped by Black in 1757.
Nitrogen was first observed by Rutherford in 1772. Oxygen,
prepared by Priestley in 1774, was recognized by Lavoisier in

ix] Doctrines of Respiration. 251

1775, and hydrogen was first made definite and clear by
Cavendish in 1781.

Thus in 1785 hydrogen was well known to Lavoisier, and he
was able to draw from the quantitative comparison of which I
have just been speaking the following important conclusion :

"Besides the part converted into carbonic acid a portion
" of the inspired vital air does not issue as it enters. There
" results therefore one of two things ; this part either unites
" with the blood or combines (in the lungs) with a portion of
"hydrogen to form water."

Had Lavoisier stopped here we should have been able to
say not only that he had in a most masterly manner solved the
general problem of respiration, but that every jot and tittle of
his work remained true and good for all time since his day.
He was however a little later on led into a false path. In 1790
he published in conjunction with the physiologist Sequin a
memoir on " The Transpiration of Animals." In that memoir
the authors give a luminous though brief exposition of the new
views which had been reached of the chemistry of the body.
They explain how digestion supplies the blood with the
material for combustion, with carbon and hydrogen, how that
material undergoes combustion, is oxidized by the respiratory
process, thus giving forth heat, and how the products of that
combustion, water and carbonic acid, are got rid of through
the skin and lungs. They clearly recognize that part only of
the water thus thrown oflf comes from the oxidation of
hydrogen, indeed a small part only, the rest being merely
the water which serves as the vehicle of the solid food. The
exposition is quite a modern one save in one point. In the
discussion on the oxidation of respiration there occurs this
remarkable sentence, "one must know in the first place that
" there transudes into the bronchi a humour which is secreted
"from the blood and which is principally composed of carbon
"and hydrogen."

The view put forward is that the oxidation of the carbon
and hydrogen supplied by the food takes place within the lungs,
in the tubes of the lungs, as the oxidation of a hydrocarbonous
fluid secreted into the tubes.

Now Lavoisier was no anatomist, was not indeed a

252 The Rise of the Modern [lbct.

physiologist, and in his other writings does not venture into
physiological as distinct from chemical hypotheses. One can-
not help suspecting that he was led astray into this wrong
hypothesis by his more distinctly physiological comrade.
However it be, the idea of the hydrocarbonous fluid laid hold
of men's minds, and was accepted as an integral part of the
new doctrine of respiration: accepted, but not by all. In
the following year, 1791, Hassenfratz, a chemist of some
reputation, who had been assistant to Lavoisier, and was now
assistant to the mathematician Lagrange, in a paper in the
Annales de Chimie, 'On the combination of oxygen with the
carbon and the hydrogen of the blood ; on the solution of the
oxygen in the blood ; and on the manner in which caloric is
set free,* expounds the following view of respiration as put
forward by Lagrange : " M. Lagrange reflecting that if all the
"heat which is distributed in the animal economy was set free
'*in the lungs, the temperature of the lungs would therefore
" necessarily be raised so much that one would have reason to
"fear they would be destroyed, and that moreover were the
" temperature of the lungs so much higher than that of other
"parts, this fact could hardly have escaped observation, con-
" eluded accordingly with great probability that the heat of the
" animal economy was set free not in the lungs alone, but in all
" parts of the body where the blood circulated."

Lagrange supposed therefore that the blood in passing
through the lungs dissolved the oxygen of the inspired air, and
that this dissolved oxygen was carried away by the blood into
the arteries and thence into the veins, and that " in the course
" of the journey of the blood the oxygen little by little quitted
" the condition of solution in order to combine in part with the
" carbon and in part with the hydrogen of the blood, and so to
"form carbonic acid and water, which are set free from the
" venous blood so soon as this leaves the right side of the heart
" to enter the lungs." And Hassenfratz relates, in support of
Lagrange's view, experiments of his own, on the changes in
colour of blood when exposed to oxygen on the one hand, and
to carbonic acid on the other; but these, which are in the
main repetitions of Priestley's earlier experiments, do not
amount to much.

ix] Doctrines of Re^iration. 253

It will be observed that Lagrange's view is the modern
view, except that we have since learnt that the oxidation
takes place, not in the blood itself, but in the elements of
the tissue outside the blood channels. Yet this view was not
accepted by all, or even generally, for some time. For many
years Lavoisier's view, or rather Sequin's, held its ground.
Even the hypothetical hydrocarbonous fluid was accepted,
though some, while still maintaining that the oxidation took
place in the lungs, supposed that the carbon and hydrogen
were oxidised while still in the blood of the pulmonary vessels,
and did not need any preliminary secretion into the pulmonary
passages.

The acute Spallanzani, laying hold of Lavoisier's discoveries
so soon as they were made known, devoted much time during
the latter years of his life to numerous experiments on the
respiration of animals, both vertebrate and invertebrate; the
memoirs embodying the results which he had obtained were not
published however until after his death, namely in 1803. In
addition to many valuable observations as to the effects of cir-
cumstances and environment, such as temperature, hybernation
and the like on the respiratory process, these memoirs contain
two far-reaching conclusions. The one is that the tissues, like
the body as a whole, respire, that is to say consume oxygen and
produce carbonic acid ; the other is that animals (snails) placed
in an atmosphere of hydrogen or nitrogen give out carbonic
acid in the same way that they do in common air.

These results really overthrew Lavoisier's theory of a hydro-
carbonous secretion; but they failed to produce their proper
eflfect, even when put forward in a more complete form many
years later, in 1823, by W. F. Edwards in his striking essay, 'The
influence of physical agents on life.' The view that oxidation
took place in the lungs, and not in the body generally, continued
to hold its own, mainly for the reason that, owing to imperfect
experimental methods, the various attempts made to shew that
blood, as demanded by Lagrange's theory, contained on the one
hand oxygen and on the other hand carbonic acid gas, fell short
of decisive results. It was not until 1837 when Gustav Magnus,
making use of the mercurial air-pump, definitely proved that
both venous and arterial blood contained both these gases.

254 Lavoisier. [lect. ix

though in different proportions, that the theory of respiration
assumed the form in which we now hold it.

Lavoisier made no reply to Lagrange; and there were
reasons why he did not.

While quite a young man, he had, against the advice of
many of his scientific friends, become connected with the
Ferme G^n^ral, as adjoint to the Fermier Baudon; and in
the midst of his glorious scientific activity he had developed
remarkable administrative powers. He did notable work of
this kind in connection with the Government manufacture
of gunpowder. His last memoir on matters connected with
respimtion, the one just mentioned as written with Sequin,
was read before the Academy of Sciences in April, 1790. This
and other of his work had been done in the midst of the
earlier storm and whirlwind of the Revolution.

The storm was now thickening, the whirlwind was growing
wilder, the days of the great terror were coming on, and
Lavoisier, and indeed the Academy, began to have enemies
among the sons of the people. In 1792 Fourcroy proposed to
purge the Academy of those suspected of leanings towards the
old order of things. In 1793, the Convention suppressed it. In
those dark days Lavoisier laboured hard to help others in the
work of science, but in the tumult he found no opportunity for
quiet research. And soon all opportunity was to be taken
away from him for ever.

The Convention arrested Lavoisier and his colleagues,
and on May 8, 1794, these were put on their trial and
condemned. Execution was swift. On the morning of May
the 9th there passed in carts from the Conciergerie to the
Place de la Revolution a procession of men to meet their
death. As the sharp stroke of the guillotine severed in turn
the neck of the fourth of these, there passed away from this
world, in his fifty-first year, this master mind of science, who
had done so much to draw aside from truth the veil of man s
ignorance and wrong thought, and there passed away too the
hope of his drawing aside yet other folds of that veil, folds
which perhaps wrap us round even to-day.

LECTURE X.

THE OLDER DOCTRINES OF THE NERVOUS
SYSTEM.

I NOW wish to turn to the views which have been held
in the past concerning the brain and the rest of the nervous
system, and concerning the way in which by means of it
sensation and movement are carried out. I cannot do better
than start with the views which were held by Vesalius.

Vesalius expounds his views on the nervous system as
follows :

" As therefore the power of the vital soul (that is the sum
" total of the vital spirit, or the vital spirit regarded as a whole)
"is situated in the substance of the heart, and the power of
" the natural soul in the proper substance of the liver, and as the
" liver prepares the cruder blood together with the natural spirit,
" and the heart the purer blood, which together with the vital
"spirit rushes with speed throughout the body, and as these
" viscera by means of the canals allotted to them distribute their
" products to all parts of the body, so also does the brain in ap-
" propriate structures, and in organs properly subserving its work,
" manufacture the animal spirit which is by far the brightest
" and most delicate; and indeed is a quality rather than an actual
" thing. And while on the one hand it employs this spirit for
"the operations of the chief soul, on the other hand it is
"continually distributing it to the instruments of the senses
"and of movement by means of nerves, as it were by cords,
" the soul never being lacking in this spirit which may be
" regarded as the chief author of the activity of those instruments,
"any more certainly than the liver and heart ever leave wholly

256 The Older Doctrines [lkct.

'' destitute, at least in health, any of the parts on which they
"bestow their products, although they do not always supply
"them either in the same quantity or the same quality.
" Nerves therefore serve the same purpose to the brain that the
"great artery does to the heart, and the vena cava to the liver,
"in as much as they convey to the instruments to which it
" ought to be sent the spirit prepared by the brain, and hence
"may be regarded as the busy attendants and messengers of
"the brain.

" The material, however, for the animal spirit, is supplied by
" the vital spirit, abounding as this does in the arteries which
" in numerous series reach both the hard and the thin membrane
"(dura mater and arachnoid) investing the brain, as also by
"the air which in breathing is drawn in towards the brain,
" on the one hand through the minute holes drilled in the sixth
" (or ethmoid) bone of the skull for the special purpose of smell,
" and on the other hand through those orifices in the skull which
" look towards the palate, as we explained very early in this work.
" And indeed air where it can find an entrance makes its way
" into the right and left ventricles of the brain, and into the
" one which lies between these. This vital spirit, although we
" may regard it as being very abundant in all the vessels and
"sinuses of the membranes of the brain is however chiefly
" brought into the right and left ventricles of the brain by the
" larger branches of the arteries which are directed to the sides
" of the gland receiving the mucus of the brain (the pituitary
"gland); offsets from these imbedded in processes of the thin
" membrane enter the lower parts of the right and left ventricle
"and then make their way over their whole extent. But
" besides these arteries a particular vessel from the fourth sinus
" of the membrana dura, passing under the body which resembles
" in shape a turtle or a chamber built in the form of an arch,
"reaches the front part of the brain by the cavity which is
" common to the right and left ventricles. This after several
" flexures divides at length into two parts, one of which passes
" to the right and the other to the left ventricle, and so joins
*' the arteries of that situation, forming a net which resembles
"the membranes of the foetus more than anything else.

x] of the Nervous System. 257

" From the air which has thus made its way into the brain,
"and from the vital spirit which on account of the numerous
"flexures becomes more and more fitted for the use of the
" brain, the animal spirit is by the special power of the brain
" elaborated in the right and left ventricles, and in the cavity
" common to the two known as the third ventricle. A portion
"(of this animal spirit) is carried from this third ventricle,
"directed through the oblong channel (aqueduct of Sylvius)
"between the bodies which resemble the nates and testes to
"the ventricle of the cerebellum (fourth ventricle) which is
"formed by the sinus of the cerebellum, and partly by the
" cavity of the beginning of the dorsal medulla (spinal cord).

** From this ventricle no mean portion of the animal spirit
"is directed into the dorsal medulla and into the nerves
"springing from it. From the other ventricles of the brain
" however the spirit is carried into the nerves springing directly
" from them, and so to the organs of the senses and voluntary
" movement.

" Meanwhile, we will not too anxiously discuss whether the
" spirit is carried along certain hollow channels of the nerves, as
" the vital spirit is carried by the arteries, or whether it passes
" through the solid material of the nerves, as light passes
"through the air. But in any case it is through the nerves
" that the influence of the brain is brought to bear on any part,
" so far I can certainly follow out the functions of the brain by
" means of vivisections, with great probability and indeed truth.''

In his chapter on vivisections, he shews how by cutting or
ligaturing this or that nerve you can abolish the action of this
or that muscle, or how having ligatured a number of nerves,
by loosing now this and now that ligature, you can bring this
and that muscle into action again, all shewing that the con-
traction of the muscle is dependent on its nerve. He mentions
incidentally that you may divide a muscle lengthwise without
stopping its contraction, but if you cut it crosswise, you do
interfere in proportion to the depth of the cut. He shews that
it is the nerve itself which is the essential agent, and not its
membranes, for you may remove the membranes without inter-
fering with movement. He further shews that if you lay bare

F. L. 17

258 The Older Doctrines [lect.

the dorsal medulla (spinal cord), and cut it across, all the parts
supplied with nerves leaving the medulla below the section will
be deprived of sensation and movement.

In the chapter on the brain from which we were quoting
he continues thus:

" But how the brain performs its functions in imagination,
" in reasoning, in thinking and in memory (or in whatever way,
" following the dogmas of this or that man, you prefer to classify
" or name the several actions of the chief soul), I can form no
" opinion whatever. Nor do I think that anything more will be
" found out by anatomy or by the methods of those theologians
** who deny to brute animals all power of reasoning, and indeed
*' all the faculties belonging to what we call the chief soul. For
" as regards the structure of the brain, the monkey, dog, horse,
'* cat, and all quadrupeds which I have hitherto examined, and
*' indeed all birds, and many kinds of fish, resemble man in
"almost every particular. Nor do we by dissection come
" upon any difference which would indicate that the functions
"of those animals should be treated otherwise than those of
" man ; unless perchance anyone says, and that rightly, that the
** mass of the brain attains its highest dimensions in man, which
" we know to be the most perfect animal, and that his brain is
" found to be bigger than that of three oxen ; and then in
" proportion to the size of the body, first the ape, and next the
"dog exhibit a large brain, suggesting that animals excel in
" the size of their brains in proportion as they seem the more
"openly and clearly to be endowed with the faculties of the
"chief soul. Indeed the more I examine the nature of the
" heart, the liver, the testes, and the organs secondary to these,
" the functions performed by which are, there can be no doubt,
" the same in us as in other animals, and the more I persuade
** myself that we ought not to draw conclusions concerning the
" operations of the chief soul, other than those taught by our
"most holy and true religion, the more I wonder at what I
"read in the scholastic theologians and the lay philosophers
" concerning the three ventricles with which they say the brain
"is supplied."

And then he goes on to ridicule the view held by these

x] of the Nervous System. 259

philosophers, Damely that a front ventricle is the receptacle
of sensations which, passed on to a second ventricle in the
middle of the head, are there used for imagination, reasoning
and thought, and that a third ventricle near the back of the
head is devoted to memory. ** Of such a kind are the figments
"of men who have never studied the handiwork of God the
"maker of all things as seen in the structure of bodies, but
"who take to themselves reckless opinions gathered from all
"manner of sources, figments imagined surely not without
"grave impiety. How wrong these are in their description
"of the structure of the brain the following discourse will
" shew.''

It is obvious that Vesalius took a distinctly physiological
view of the origin of the chief soul. The chief soul is to him
the totality of the animal spirits just as the vital soul is the
totality of the vital spirits ; it is engendered in the brain by
" virtue of the powers of the proper material and form of the
brain,'' just as the vital soul is engendered by the substance of
the heart ; or as we should say in modern language, psychical
phenomena are the outcome of the activity of the nervous
tissues. And from the way in which he not once only but
repeatedly scoflfs at the philosophers who deny to brute beasts
all the principal functions of the chief soul, though the brains
of these are so like that of man, we may infer that he nursed
in secret the belief that future inquiry would make clear the
hidden meaning of the complicated structure of the brain, and
shew how its several parts were concerned in the diflferent
activities of the souL But the time for that had not yet come.
Even the preliminary step, an adequate psychological analysis
of the faculties of the soul, was as in his opinion yet wanting ;
and he refused to waste his time in speculations, the conclusions
of which could not be tested either by anatomical observation
or by vivisectional experiment. He was clear that the soul
was engendered in and by the brain, but beyond that he knew
next to nothing. Vivisection taught him that when the brain
is removed, sensation and movement are lost ; but it taught him
little more than this. He was not to be led into a quarrel with
the Church, by indulging in speculations having no solid basis.

17—2

260 The Older Doctrines [lect.

" And so the learned anatomist trained in the dissection of dead
"bodies, and tainted with no heresy, will readily understand
" how little I should be consulting my own interests were I to
" lecture on the results to be obtained by the vivisection of the
" brain, which otherwise I would most willingly have done, and
"indeed at great length."

In this as in almost everything else which Vesalius wrote
there is a wholly modem ring. We seem to be stepping
backwards again when nearly a hundred years later we come
to the views of van Helmont and Descartes. I put these
together, for the sensitive and motive soul of van Helmont
and the rational soul of Descartes, though the latter includes
van Helmont's immortal mind, are alike in this that they are
both outside and distinct from the animal spirits, the activities
of the nervous tissues themselves. That the seat of the soul
is placed by one in the pylorus and by the other in the pineal
gland is a matter of indiflTerence. The essential point of both
views is that the soul is something added to, diflferent from the
mere results of the action of the tissues of the brain. This
permitted Descartes to accept and make use of the strictest
physical conceptions of the nervous phenomena themselves.

To Descartes the whole body was nothing but a machine
whose motive power lay in that heat which was innate in the
heart though fed and sustained by the food carried to it in
the blood ; in this respect he, rejecting the modem doctrines of
Harvey and others, followed the teaching of the ancients. To
him the whole body was nothing but a machine, in which the
blood, heated and rarefied in the heart, engendered " the very
" subtle air or rather the very lively and pure flame, called the
"animal spirits," which in turn in that part of the machine
called the brain and nervous system on the one hand carried
out according to simple physical and mechanical laws all the
movements of the body in response to changes in the environ-
ment, and on the other hand, by supplying the physical basis
for and by working on the rational soul, gave rise to modifica-
tions of thought.

Though he speaks of the animal spirits as an * air' or a
* wind ' or a * flame,' yet throughout he treats them as if they

x] of the Nervous System. 261

constituted a fluid, a fluid very subtle indeed and of a wholly
peculiar nature, but still a fluid and so far amenable to the
physical laws governing fluids. It was in his time a doctrine
daily gaining ground that the nerves were tubes along which
the animal spirits flowed. Laying hold of this doctrine and
making use of some known general facts of the topography of
the brain and nerves, he constructs an ideal nervous machine
consisting of the brain as a centre and of nervous tubes radiating
from this centre and carrjdng the animal spirits to all parts
of the body. And, in order to make the exposition of the
working of this machine clear and convincing, he does not
hesitate to attribute to its various parts features which he
describes as if they belonged to the common knowledge of
the time, though neither he nor anyone else had actually
seen them.

His exposition of the general working of the machine is as
follows :

"For you must know that the arteries which bring the
"blood from the heart after having divided into an infinite
"number of small branches and having formed the delicate
"tissue which is spread like a carpet over the floor of the
" ventricles of the brain, are gathered together round a certain
" little gland which is placed about the middle of the substance
"of the brain, just at the entrance into the ventricles. And
" these arteries have in this situation a large number of minute
" orifices through which the more subtle particles of the blood
"which they hold can flow into this gland but which are so
" narrow that they do not permit any passage through them of
" the grosser particles.

" You must also know that these arteries do not end there
"but, being gathered together again, several into one, they
"ascend straight upwards and join the great vessel, which
" is like a Euripus, and which bathes the outer surface of the
"brain. And it must be noticed that the grosser particles of
" the blood lose a great deal of their agitation in the turns and
" twists of the delicate tissue through which they pass, the more
" so that they have the power to impinge on the smaller more
" subtle particles mixed with them and to transfer their move-

262 The Older Doctrines [lect.

'' ment to these. But these more delicate particles are not able
"in the same way to lose their movement, which indeed is
"increased by the movement transferred to them from the
"grosser particles, since there are no other bodies in their
" neighbourhood to which the latter can so easily transfer their
" movement.

"Hence it will be easily understood that these grosser
" particles, as they ascend straight up towards the outer surface
" of the brain where they serve for the nutrition of its substance,
"bring it about that the more delicate and more agitated
" particles are turned aside, and all enter into this gland, which
" must be regarded as a very full reservoir whence the spirits at
" the same time flow into the ventricles of the brain. Thus,
" without any other preparation or change except that they are
" separated from the grosser particles and that they still retain
" the extreme velocity which the heat of the heart has given
"them, they cease to have the form of blood and are called
"animal spirits.

"Now as these spirits enter thus into the ventricles of the
"brain, so they pass thence into the pores of its substance and
"from these pores into the nerves. And according as they
" enter or even only as they tend to enter more or less into
" this or that nerve they have the power of changing the form
" of the muscle into which the nerve is inserted and by this
" means of making the limbs move. You may have seen in the
"grottoes and fountains which are in our royal gardens that
" the simple force with which the water moves in issuing from
"its source is suflScient to put into motion various machines
" and even to set various instruments playing or to make them
" pronounce words according to the varied disposition of the
"tubes which convey the water.

" And indeed one may very well compare the nerves of the
" machine which I am describing with the tubes of the machines
" of these fountains, the muscles and tendons of the machine
"with the other various engines and springs which serve to
"move these machines, and the animal spirits, the source of
" which is the heart and of which the ventricles of the brain
" are the reservoirs, with the water which puts them in motion.

x] of the Nervous System. 263

" Moreover breathing and other like acts which are natural and
" usual to the machine and which depend on the flow of the
" spirits are like the movements of a clock or of a mill which
" the ordinary flow of water can keep going continually. Ex-
**temal objects, which by their mere presence act upon the
"organs of sense of the machine and which by this means
" determine it to move in several different ways according as
" the parts of the machine's brain are disposed, may be compared
" to strangers, who entering into one of the grottoes containing
"many fountains, themselves cause, without knowing it, the
"movements which they witness. For in entering they
"necessarily tread on certain tiles or plates, which are so
"disposed that if they approach a bathing Diana, they cause
" her to hide in the rosebushes, and if they try to follow her,
" they cause a Neptune to come forward to meet them threat-
"ening them with his trident. Or if they pass in another
"direction they occasion the springing forward of a marine
"monster who spouts water into their faces, or things of a
"like kind according to the caprice of the engineers who
"constructed them.

" Lastly, when the rational soul resides in this machine, it
" has its principal seat in the brain and may be compared to
"the fountaineer who has to take his place in the reservoir
** whence all the various tubes of these machines proceed
"whenever he wishes to set them going, to stop them or in
"any way to change them.*'

Thus the pineal gland, " the little gland in the middle of
the substance of the brain," is the primary reservoir, and the
ventricles of the brain form a secondary reservoir of the animal
spirits, which flowing from the brain along the tubular nerves
carry out the movements of the body, the energy of these
spirits being supplied by the innate heat of the heart. He
explains in the following manner the particular way in which
the working of this nervous machine is determined by the
impressions of external objects. The nerves are not mere
hollow tubes, provided with valvular arrangements by means of
which the flow of the animal spirits outwards from the brain to
the muscles and other structures is regulated; they contain

264 The Older Doctrines [lect.

also within their cavities, delicate threads, forming a sort of
marrow, and these threads by centripetal action determine the
outflow of the spirits from the gland and from the ventricles
into the nervea

" You see also that in each of these little tubes there is a
"sort of marrow composed of a large number of exceedingly
"delicate threads starting from the proper substance of the
" brain." (He explains elsewhere that the proper substance of
the brain forming the walls of the ventricles is composed of an
intricate network of these delicate threads, the meshes of the
network being the pores or mouths of the tubular nerves.)
" The ends of these threads terminate on the one hand at the
"internal surface of the brain looking towards the ventricles,
" and on the other hand in the skin or other tissues in which
" the tubes which hold them end. But, since this marrow does
** not serve for the movement of the members " (is not motor in
function as we should say but sensitive only), " it will be enough
" at the present moment if you know that it does not wholly
"fill the tube which holds it so that the animal spirits have
" ample room to flow readily from the brain to the muscles to
" which these little tubes, which ought here to be considered as
" so many little nerves, are distributed.

♦ ♦ ♦ ♦ ♦

" Know then that a very large number of little threads like
"the above begin to separate all of them, the one from the
"other, at the internal surface of the brain where they take
" their origin, and spreading thence over all the rest of the body
" serve as organs of sense.

« « « « «

"In order to understand how the brain can be excited by
" external objects which affect the organs of sense, so that all
"the members can be moved in a thousand different ways,
"imagine that the delicate threads, which as I have already
" said arise from the inside of the brain and form the marrow
" of the nerves, are so disposed in all those parts which serve as
" the organs of any sense that they can easily be set in motion
" by the objects of the senses, and that, whenever they are thus set
" in motion, even ever so little, they, at the same instant, pull

xj of the Nervous System. 265

"upon the parts of the brain whence they take origin, and
"by this means open up the orifices of certain pores which
"exist on the internal surface of the brain. Through these
"pores the animal spirits which are in the ventricles imme-
" diately begin to make their way and thus pass into the nerves
"and so into the muscles which carry out in the machine of
" which we are speaking movements exactly like those to which
" we ourselves are incited when our senses are aflfected in the
"same way.

"If for example fire comes near the foot, the minute
"particles of this fire which as you know move with great
" velocity, have the power to set in motion the spot of the skin
" of the foot which they touch, and by this means pulling upon the
" delicate thread which is attached to the spot of the skin, they
"open up at the same instant the pore against which the
" delicate thread ends, just as by pulling at one end of a rope
" one makes to strike at the same instant a bell which hangs on
"the other end."

According to Descartes then the movements of the body
viewed as * an earthly machine ' are brought about by that part
of the brain which forms the walls of ventricles serving as
centre where the play of sensitive impulses communicated by
the delicate threads of the marrow of the nerves determines
the outflow of the motor animal spirits along the tubular
channels of the nerves. And making use of the physical
properties of the delicate threads on the one hand, and of
the subtle but powerful fluid, the animal spirits, on the other
hand, by the help by various devices such as valvular arrange-
ments in the nerves, the existence of which he takes for
granted, he gives a detailed exposition of the varied working
of the machine. He does not hesitate to assume the existence
in the nerves of various physical properties and to explain by
means of them various nervous and even psychical phenomena.
He finds for instance the physical basis for habit and memory
in the following :

" Consider also that an important feature of these delicate
" threads is the property of being easily bent in every kind of
" way by the mere force of the spirits which press upon them

266 The Older Doctrines [lkct.

*" and of retaining, just as if they were made of lead or of wax
" as it were, the shape into which they were last thrown until,
•* by some further action, they are made to assume a new one."

The ventricles of the brain however do not form the only
reservoir of the animal spirits; another and more important
reservoir is the pineal gland. This moreover is the only part
of the brain to which is attached the rational soul ; this is " the
seat of imagination and of common sensation.** Through it the
rational soul can directly bring about body movements and
through it external objects are able to impress the soul. He
developes a mechanical theory explaining how the movements
of the spirits from the surface of the pineal gland are correlated
to the movements of the spirits at the internal sur&ce of the
ventricles, the entrance into the pores of the latter affecting
the outflow from the pores of the former, and gives an interest-
ing exposition of how in the action of external objects on the
delicate threads of the nerves there is a double event, a primary
event by which impulses from external objects *' impress their
figure" on the internal surface of the ventricles, and a secondary
event by which a corresponding figure is impressed on the
surface of the pineal gland and so on the soul. The first,
serving as a relay, is as we should say a purely nervous, the
latter a psychical, event.

"Not those figures which are impressed on the external
" organs of the senses or on the inner surface of the ventricles
" of the brain, but only those which are traced in the spirits on
"the surface of the pineal gland can be considered as ideas,
" that is to say as the forms or images of which the rational
"soul will take direct cognizance, when, being united to the
"machine, it imagines or feels any object."

And he takes advantage of the mobility of the pineal gland
to offer a mechanical explanation of psychical phenomena.
"Consider moreover that the gland is composed of very soft
" material and that it is not completely joined and united to
"the substance of the brain but only attached to the small
" arteries (the walls of which are very loose and flexible) and
" that it is kept balanced by the force of the blood which the
"heat of the heart drives towards it. Hence it needs very

x] of the Nervous System. 267

" little to determine it to incline or to lean now on this side,
" now on that, and to bring it about that in leaning it disposes
"the spirits which issue from it to direct themselves towards
" certain parts of the brain rather than towards others." The
rush of spirits determined by the action of the impression of an
external object makes the pineal gland lean on one side, the
result of which is that, the disposition of its pores being changed,
these on the one hand permit a freer outflow of certain spirits
"so that the idea which these spirits form becomes more
"perfect," and on the other hand hinder the issue of other
spirits, moved by some other object "so that you see, how
"one idea prevents another being received."

In anticipation as it were he rejects beforehand the views
which were later on brought forward by Stahl. Putting aside
the direct actions of the rational soul, all other vital phenomena
are the results of pure machinery ; he admits no necessity to call
in the aid of spiritual agencies to explain these ; they are to be
explained like all other physical phenomena of the universe, by
the aid of the new mechanical philosophy.

This is what he says :

"All the functions of the body follow naturally from the
" sole disposition of its organs just in the same way that the
" movements of a clock or other self-acting machine, or auto-
" maton follow from the arrangement of its weights and wheels.
"So that there is no reason on account of its functions to
"conceive that there exists in the body any soul whether
" vegetative or sensitive, or any principle of movement other
"than the blood and its animal spirits agitated by the heat
"of the fire which bums continually in the heart and which
"does not diflfer in nature from any of the other fires which
"are met with in inanimate bodies."

The prerogative of the rational soul is thought ; the soul
understands, wishes, imagines, remembers and feels, for all these
are modes of thought ; everything else is the work of the bodily
machine, sometimes actuated by the soul but sometimes not ; and
the soul always acts through the machine. "The soul can call
" forth no movement in the body unless all the corporeal organs
" needed for the mbvement are properly disposed. On the other

268 The Older Doctrines [legt.

*' hand when the body has all its organs properly arranged for
" a particular movement, it has no need of the soul to carry
" this out. Hence all movements except those which we tnow
"to depend upon thought ought not to be attributed to the
" soul but to the mere disposition of organs, and even the move-
"ments which we call voluntary depend principally on the
" same disposition of the organs (though it is the soul which
"is the determining cause) since without such a proper
"disposition we cannot carry them out, however much we
" will to do so. Because the movements cease when the body
" dies and the soul quits it, we must not therefore infer that it
"is the soul which produces them, since it is one and the same
" cause which on the one hand renders the body unfit to produce
" the movements and on the other hand leads the soul to quit
"the body.'*

If we judge Descartes from the severe standpoint of exact
anatomical knowledge, we are bound to confess that he, to a
large extent, introduced a fantastic and unreal anatomy in
order to give clearness and point to his exposition. From this
standpoint we cannot consider him as contributing to the
progress of physiology ; he stands in this respect wholly aside
from Harvey or from other men of whom we are about to speak.
On the other hand, however, we must admit that he did succeed
in shewing that it was possible to apply to the interpretation
not only of the physical but also of the psychical phenomena of
the animal body, the same method which was making such
astounding progress when applied to the phenomena of the
material world. And indeed a very little change in the details
of Descartes* exposition and some of that hardly more than a
change in terminology would convert that exposition into a
statement of modern views. If we read between the lines
which he wrote, if we substitute in place of the subtle fluid
of the animal spirits, the molecular changes which we call a
nervous impulse, if we replace his system of tubes with their
valvular arrangements by the present system of concatenated
neurons, whose linked arrangement determines the passage and
the effects of the nervous impulses, Descartes* exposition will
not appear so wholly different from the one which we give to-day.

x] of the Nervous System. 269

Descartes was a philosopher, uot a physiologist. He took
interest in the problems of the living body only so far as they
bore on the greater problems of the why and the wherefore of
the universe. He entered into the details of vital functions
and mingled in the controversies concerning them incidentally
only, with the view of establishing or supporting his philo-
sophical position. We must now turn back again to the
physiologists proper.

Though Malpighi as we have seen devoted much attention
to the histology of the nervous system, we find in his writings
very little concerning its functions ; and indeed an inquiry of a
kind which must sooner or later lead the investigator into
baseless speculations, and, at that time at least, any research
into the properties of the nervous tissues seemed to be such,
was wholly uncongenial to the character of his mind. Nor did
this part of physiology appear to offer great attractions to many
of the other men of the seventeenth century who were devoting
themselves to exact anatomical and physiological research.
One man alone perhaps during this century stands out promi-
nently for his labours on the structure and functions of the
brain, namely Thomas Willis.

Born at Great Bedwyn in Wiltshire on Jan. 27, 1621,
Willis was educated at Oxford, where he took his M.A. degree
in 1642. Remaining at Oxford, he was led in 1646, while
that city was " garrisoned for the King," to employ his enforced
leisure in the study of physic ; and he eventually took up the
profession of medicine. An enthusiastic royalist and staunch
churchman, he was rewarded, upon the Restoration, by being
made Sedleian professor at Oxford ; and for some years he was
active there, practising his profession, fulfilling the duties of
his chair, and pursuing scientific researches. He was con-
spicuous among the band of men, who in those years laid at
Oxford the foundations of the Royal Society. In 1666 however
he moved to London, **went," says Wood, "to the city of
" Westminster, took a tenement in Saint Martin's Lane, and in
" a very short time after he became so noted and so infinitely
" resorted to, that never any physician before went beyond him
" or got more money yearly than he. At length after a great

270 The Older Doctrines [lect.

" deal of drudgery that he did undergo in his faculty (mostly
" for lucre sake) which did much shorten his life, he concluded
" his last day in his house in Saint Martin's Lane afore men-
"tioned on the 11th day of November 1675."

Willis was not like Descartes a philosopher, and indeed was a
man of a wholly different order ; but he possessed what Descartes
did not, a practical knowledge of the details of the structure
and functions of the body and especially of the brain in health
and disease. His work on the brain, by which our knowledge
of cerebral structures was advanced far more largely than is
indicated by the mere addition to anatomical nomenclature of
the term ' circle of Willis,' became a classic work. The value
of the book is indeed much above the worth of the author.
Willis himself acknowledges that in his researches on the
brain he was much assisted by Richard Lower; and Wood
speaking of Lower says, "Willis whom he helped or rather
instructed." Lower as we have already seen was a real
man of science, with a clear penetrating mind, with a
genuine love of truth for truth's sake, a worthy mate of
Boyle, of Hooke and of Mayow. Willis was of a different
type; love of truth was in him less potent than love of
fame. Mixing with and indeed in daily intercourse with the
band of exact inquirers, who at Oxford and in London were
striving to establish the new philosophy and advance by
experiment natural knowledge, Willis caught up their phrases
and thinking himself one of them, attempted to expound in
their fashion the physiology of the nervous system. But his
method, when he was left to himself, and deprived of the aid
and guidance of Lower was, in reality, wholly different from
theirs. They made exact observations and careful experiments
and, guided by the dry light of reason, drew conclusions with
caution, and expounded them with brevity, using words only as
expressing the meaning of things. Willis's mind was of the
rhetorical sort, he loved words as words, looked upon an
illustration as an argument, and when he discovered an analogy
thought he had found a proof. Hence when we come to
examine the views which he put forward, we find that while
they are expounded with a certain philosophic air which perhaps

x] of the Nervous System. 271

goes far to explain the influence which they had in their time,
they do not of themselves form any real solid contribution to
knowledge. They are indeed to a large extent the views of
Descartes, modified by more exact anatomical knowledge, oc-
casionally by sound physiological deductions, in which we may
probably trace the influence of Lower and other of Willis's
contemporaries, but chiefly and especially by certain conceptions
and certain modes of expression which appear to be entirely
Willis's own.

He admits with Descartes that man possesses a rational
soul, an immortal, incorporeal soul, but that, putting aside
everything which is due to the direct activity of this rational
soul, the nervous as well as the other phenomena both of man
and of animals may be regarded as the phenomena of a
corporeal machine. While, however, Descartes makes it his
first object to prove that the body of man is, in this way, a
machine, and that all known physiological phenomena may be
adequately explained on this hypothesis, and has a secondary
interest in physiological problems as such, caring for them only
so long as they illustrate his thesis, Willis is especially con-
cerned with these same special problems and in no case dwells
on Descartes' main thesis.

Descartes speaks only of the animal spirits, accepting oflF-
hand, as we have seen, the old views concerning them, but
treating them from an exact physical point of view. Willis, in
his rhetorical way, speaks of these animal spirits as constituting
part of a corporeal soul, to whose activity are due the nervous
phenomena of man and the higher animals ; and he is especially
concerned with the features and mode of action of this corporeal
soul, this soul of the mere machine. He puts forward the
view that this corporeal soul consists of two parts, one residing
in the blopd, the other in the brain and nervous system ; and
he believed that he had made a great discovery in recognizing
the exact nature of these two parts of the soul. As I have said,
Willis's mind was of that sort which when it has hit on an
illustration or discovered an analogy, thinks it has found a proof.
And the great discovery was simply this, that the part of the
soul residing in the blood was of the nature of 'flame,' and

272 The Older Doctri^ies [lect.

the part residing in the brain and nervous system was of the
nature of ' light/ This is what, in his rhetorical way, he says :

" The corporeal soul common to man and the higher animals,
"while it extends over the whole organic body and vivifies,
" actuates and irradiates every part, both tissues and humours,
"yet seems more eminently to subsist in two of these, and
" to hold them as its imperial seats as it were. These subjects
"of the soul are on the one hand the vital fluid, the blood,
"circulated in a perpetual round in the heart, arteries and
"veins, and on the other the animal fluid or nervous juice
" streaming gently through the brain and its belongings. Both
" these provinces the soul inhabits and adorns with its presence,
" but since the whole soul cannot be in both provinces at the
" same time, it is as it were divided, it actuates each province
" by its appropriate half One of its halves, since it is as we
" have shewn of the nature of fire, glides into the blood after
"the fashion of a lighted flame, while the other half seems
"diflFused through the animal fluid after the manner of light,
" like the rays of light emanating from that flame, rays which,
" taken up by the brain and the nerves as by dioptic glasses
"and manifoldly reflected or refracted, form various figures
" according to the workings of the animal faculties.

" The animal soul therefore, corresponding to its dual chief
" functions in the animal body, consists of two distinct parts,
" namely, flame and light ; for as regards the functions called
" natural, these are in truth only involuntary animal functions
" and are carried out by the aid of animal spirits."

He devotes a special treatise to prove that the blood
is aflame, is burning, that a flame exists in the blood.
He had, as I have said, many sound physiological views.
He says of the blood : " The functions of the blood at
"least in the higher animals are diverse and manifold.
"It instils into the brain and nervous system materials
"for the animal spirits, it provides nutritive juice for the
"various tissues, it supplies the elastic link to the motor
"structures, and besides secretes various residues and effete
"particles, and deposits them in the appropriate emunc-
"tories." Nor can even modem physiology find fault with

x] of the Nervous System, 273

the following argument. "The following three things are
*' especially essential requisites for the maintenance of a flame.
*' In the first place a free and continuous access of air must be
" allowed to the flame so soon as it is lighted. In the second
" place the flame must enjoy a constant supply of sulphureous
" (combustible) material. In the third place the products of
"the flame whether gaseous or solid must be continually
"removed." All these conditions are met with in the body.
Fresh air is supplied by breathing, sulphureous material is
furnished by the food, and the products of the flame in the
blood are removed by excretion through the skin.

He naturally finds a difficulty in the fact that the flame of
the blood is not visible ; but this difficulty is not insuperable.

" But indeed the blood might be actually in flames and yet
" the light of it, on account of its tenuity, might not be visible
"to our eyes. We know that in the clear light of day we
''can see neither red-hot iron nor fireflies, nor ignes fatui nor
" (phosphorescent) rotting wood, nor many other things which are
" visible at night. Why then should not the vital fire, much
" lighter than any of the above, escape our vision ? Moreover
" sometimes warm-blooded animals are wont to emit a visible
" flame or fire at night only. For instance we have known
" certain folk endowed with a warm and vaporous blood who
"in the evening when on going to bed they take off their
"underclothing near a fire or a candle, have emitted a very
"delicate and shining flame which lit up all the lower parts
" of their body. The cause of the above seems to be the same
"as that by which a torch just put out and still smoking is
" relighted by the merest trifle, shewing that a kind of flame,
" the root of the one outside, lay hid in the torch. For the
" same reason again the coats of horses, mules, cats and other
" warm-blooded animals, when rubbed give rise to sparks which
" in the dark may amount to a really conspicuous light.'* And
he goes on to quote the case of '"an ingenious man with an
" active brain who said that after an extra good bout of wine
"he could see to read print clearly on a very dark night."

Willis, as the above shews, had no great critical power in
judging the value of evidence, and he was led to this idea of

F. L. 18

274 The Older Doctrines [lect.

the flame of the blood, more by the force of the simile than by
reasoning on facts ; nevertheless, as the pupil of Harvey and as
a comrade of the chemists of the day, he had laid hold of the
view that the heat of the body is the heat of combustion, and
in this respect was far above the old idea of the heat innate in
the heart to which Descartes clung. He rejects this old idea
in the words, " The heart gets its heat from the blood, not the
"blood from the heart."

Having satisfied himself that the active properties of the
blood, the vital spirits of the old teaching, are of the nature of
flame, the same trust in the force of illustration led him to
maintain that the active properties of the nervous system, the
animal spirits, were of the nature of light.

"Although it is clear enough that such spirits are the
" causes of animal functions and constitute the basis of the soul
" itself, nevertheless it seems very difficult to explain what they
" are in their own proper essence, since scarcely anything occurs
"in nature with which in all respects they are comparable.
" The comparison of these with spirits of wine, of turpentine or
" of hartshorn, and the like, is by no means suitable. Besides
"that these chemical liquids neither represent the images of
" objects, nor exercise any elastic force, as do the auimal spirits,
"they are moreover less subtle and volatile than these, since
" they can be poured or distilled from one vessel into another,
"whereas the animal spirits, vanishing directly that life is
"extinct, leave no trace of themselves behind. Wherefore we
"may far more rightly, according to our hypothesis, say that
" these spirits, emitted from the flame of the blood, are like rays
" of light, at least these joined with those of wind and air. For
"just as light is moulded to the impressions of all visible things,
" and air is moulded to the impressions of all audible things, so
" the animal spirits receive the images impressed on them, not
" only of the above, but also of odours and all tang ible qualities,
" and deposit them in the common sensorium. But the air or
" aerial particles, so long as they are free and unmixed, create
" no rush or tumult, yet when closely confined in clouds, or in
"machines, or brought into contact with sulphurous and other
" elastic corpuscles, being forthwith made wild, burst forth into

x] of the Nervous System. 275

" often dreadful meteors, namely winds, whirlwinds and thunder.
" In the same way the animal spirits, so long as they are pure and
" are carried in the open spaces of the brain and its appendages,
" behave tranquilly enough, but when shut up within muscles,
" and these permeated with sulphurous particles from the blood,
"and sometimes with heterogeneous matter in other places,
" become exceedingly impetuous, that is elastic, or spasmodic/*

Though he hugged this idea of the animal spirits, the basis
of the corporeal soul, being of the nature of light, Willis was
no physicist. He caught up the phrases of his friends, Boyle
and others, without understanding them, and when he comes
to explain nervous phenomena, he mixes up the properties of
light with other physical phenomena, and indeed with chemical
phenomena. He speaks of the lighter, more spirituous parts
of the blood, as ascending by the carotid and vertebral arteries,
and as being distilled in the brain, and so prepared, as in a
chemical operation, into animal spirits. These animal spirits
are prepared in the cerebrum and cerebellum alone, in the
cortex of each, and thence diflfused over the whole nervous
system. There are different kinds of animal spirits; those
prepared in the cerebrum are destined for voluntary movement
and sensation, those in the cerebellum for involuntary move-
ments, for the beat of the heart, respiration and the like.
These latter are simple, and have not the diversity of voluntary
movements, hence the folds of the cerebellum, unlike those of
the cerebrum, are all alike.

When, however, he discusses what we may call the general
phenomena of nervous action he has recourse to the physical
phenomena of fluids. The animal spirits pervade the whole
nervous system, but in a special way. The nerves are not
tubes along which the spirits flow, but solid fibres, and the
animal spirits pass along them as spirits of wine pass along the
stretched dry strings of a fiddle. This is how he explains
nervous action:

" The internal and immediate efficient cause both of sense
" and movement is furnished by the basis of the sensitive soul,
"that is to say, by the animal spirits instilled into the brain
" from the blood which is alight, and thence diffused into the

18—2

276 The Older Doctrines [lect.

" nervous system. These, being distributed by the brain, as from
" a fount, along the nerves over the whole body, imbue, irradiate,
"and fill all parts, inducing in each a certain tenseness. So
"that the ducts of the nervous structures, like cords lightly
"strung, are extended from the brain and its appendages in
" every direction to all peripheral parts. And these are so strung
" and so actuated by a certain continuity of the soul (the corporeal
" soul), that if either extremity be struck, the blow is forthwith
"felt throughout the whole. Hence any intention conceived
" within the brain immediately carries out the purposed work
" in the proper member or part, and vice versd, any impulse or
" blow which is inflicted from without on any member or sensitive
** organ is immediately communicated to the brain. When the
^'impression or impetus passes outwards from the brain along
*' the nerves to motor structures, movement is produced. If on
" the other hand the impression started from without is carried
"inwards towards the brain, sensation is the result. While
"either of these is taking place, we must not suppose (as is
" commonly stated) that the same spiiits rush at once from one
"goal to another as in a race-course or circus, and then rush
"back again; but since the soul by reason of a certain con-
" tinuity is expanded over the whole, and its particles, that is
" to say the spirits, are arranged touching each other, drawn up
" as it were in line, so these, in military fashion, perform their
" functions, keeping their ranks without leaving their stations,
" and whether arranged in active fighting order, or passively as
"a mirror, themselves immobile, on the one hand obey the
'* commands of the brain sent down from without, and so bring
^* about movements, or on the other hand, pass straight on to
"the brain the message impressed on them by the sensitive
"structures, and thus give rise to sensation. So the same
" animal spirits bring about both movement and sensation, by
"their own opposite and inverse disposition and aspect."

And he explains diversity of functions by the argument,
"that it does not seem contrary to reason to suppose that
" within the basis of the sensitive soul and indeed within the
" same part of it, certain spirituous particles may be in move-
"ment while others remain at rest."

x] of the Nervous System, 277

In the above Willis may be regarded as dimly striving to
explain nervous phenomena on the hypothesis of a specific
nervous fluid, possessed of peculiar properties, a kind of fore-
shadowing of an electric fluid. But when he comes to explain
the functions of the several cerebral structures he falls back on
his hypothesis of nervous action being light, or rather he falls
back on his illustration of light. Though the basis of the
sensitive soul, namely the animal spirits diffused through the
whole nervous system, is a physical, elastic fluid, the impres-
sions on it which are developed into sensations are no longer
regarded as impulses, as in the passage which I quoted just
now. but as optic images.

The impressions made upon the sensory nerves by all
external objects pass through the middle parts of the brain,
through the crura cerebri to the corpora striata, thence to the
corpus callosum and so to the cortex. This is what he says :

*' As regards the various functions and duties of the spirits
" thus aiTanged in separate provinces, in the first place we allot
"to them a twofold feature, one by which they work inwards
"to carry on sensation, another by which they work outwards
" to carry on movement. More particularly it seems allowable
" to conceive of the middle regions of the brain as constituting
"an inner chamber of this soul fitted with dioptric mirrors,
"as with windows. The pictures or images of all sensible
"things admitted into these secret places by means of the
" ducts of the nerves, as by means of tubes or narrow openings,
" first pass through the corpora striata, which serves the purpose
" of an objective glass, and then are represented on the corpus
"callosum as on a whitened wall. And so the things which
" give rise to sensation induce perception and a certain imagi-
" nation. These images or pictures thus formed there very
"often produce nothing but the mere knowledge or sensation
" of the object, but presently or at times having passed on, as
"it were by a second undulation from the corpus callosum
" towards the cortex of the brain, and being stored in its folds,
" give rise to the memory of the thing, though the mere image
"vanishes. But if the particular sensation impressed on the
"imagination gives promise of something good or evil, forth-

278 The Older Doctrines [lect.

" with the spirits being excited, look back upon the object by
"whose impulse they are set in motion, and for the sake of
** laying hold of it, or of driving it away, very quickly delegate
*' to other spirits flowing along the ducts of the nerves, and so
"on to other spirits of the members and of the motor parts,
" occupying their proper places, the orders to carry out the
" appropriate movements. Thus sense gives rise to imagination,
" this to memory or to impulse, or to both of them, and impulse
" finally gives rise to local movements, which bring about the
" performance or the avoidance of the apparent good and evil."

Thus all sensory nerves carry their impulses (as we now
call them) to the corpora striata, which Willis repeatedly
speaks of as the sensorium commune, the common seat of
sensation, and produce fiirther effects, first in the corpus
callosum and then in the cortex. The same path is taken
in the reverse direction by the motor impulses started by
affections of mind. These also pass by the corpora striata,
which Willis appears to have recognized as important organs
no less of movement than of sensation; and his medical
experience enabled him in many cases to connect disease in
them with the symptoms of paralysis. We may add in passing
that the same experience, as well as the results of his
anatomical researches, led him to suppose that the optic
thalamus was especially connected with sight.

I must not however tarry longer on Willis and his views ;
yet I cannot refrain from quoting one more passage which on
the one hand shews that he had dimly laid hold of the modem
doctrine of reflex action (and indeed other passages shew this),
and on the other hand illustrates the difliculty which he met
with in explaining all the phenomena of brute beasts by the
mere possession of a material corporeal soul in the absence of
that rational soul which belonged to man alone.

" We may admit that the impression of an object, driving
" the animal spirits inwards, and modifying them in a certain
"peculiar manner, gives rise to sensation, and that the same
" animal spirits in that they rebound from within outwards in a
" reflected wave as it were, call forth local movements. We have
" not, however, as yet stated how this soul or some part of it

x] of the Nervous System. 279

" perceives that it feels, and in accordance with that perception
"is driven into various passions and actions, is turned to the
** desire of this or that object, and sometimes, as we may at
** times observe in certain beasts, in following up the thing
"sought for, enters upon and carries out acts which seem to
"have no other source thsin judgment and a certain deliberation.
" Of course in man we can readily understand that the rational
''soul, the governor as it were, looks upon the images and
"impressions presented to the rational soul as to a mirror,
"and according to the conceptions and notions thus derived
" exercises the acts of reason, judgment and will. In what way
"however in brute beasts, perception, the discrimination of
" objects, desire, memory and other forms of so to speak lower
" reason, are carried out seems very difficult of explanation."

Willis's views did not escape severe criticism on the part of
his contemporaries and even of his friends. John Mayow's
strictly scientific spirit led him to apply to Willis's rhetorical
expositions the following words :

" We have no need of I know not what vital flame by whose
" deflagration the whole mass of the blood is heated, the heart
"living like a salamander untouched in the midst of the flames.
" Much less are we to suppose that such an intense heating of
" the blood takes place as to be strong enough to give rise to
" light, the rays of which, transmitted to the brain, are to
"be thought to foi-m the sensitive soul."

And again,

"As regards this lucid soul which dwells in the brains of
"animals, I ask how it comes about that the light which is
" supposed to illumine the whole brain and all the nerves can
" never be seen by the eye ? Assuredly Fires of this kind and
" New Lights no less in Anatomy than in Religion appear to
" me things wholly vain and fanatic."

The gifted Stensen also, in the remarkable lecture "On
the Anatomy of the Brain," to which I have already referred,
criticised very severely the views both of Descartes and of
Willis. The burden of the lecture is that the anatomy of the
brain is, for technical reasons, the most difficult part of all
anatomy, and that, in spite of all that has been done, our

280 The Older Doctrines [lect.

knowledge of the real nature and disposition of the elements of
the nervous system is most meagre.

"There abounds indeed a rich plenty of men to whom
"everything is clear. Such, dogmatizing with the utmost
" confidence, make up and publish the story of the brain and
"the use of its several parts with the same assuredness as if
" they had mastered with their actual eyes the structure of so
" admirable a machine and penetrated into the secrets of the
"great artificer." Stensen perhaps especially directed this
sarcasm against Descartes, whose merit as a philosopher,
however, as we have seen, he duly recognised ; but he doubt-
less had in his mind Willis also, with whose mere anatomy
moreover he found fault, complaining of his figures as being
inaccurate.

Stensen refused to admit, in face of the lack of all sound
anatomical knowledge, any physiological deductions whatever.
After pointing out a number of cases in which he shews that
adequate anatomical knowledge is wanting, he says, "whence you
" may guess how little trust is to be put in explanations based
"on such a futile foundation." "I have said nothing of the
"use of parts, nothing of the actions which we call animal,
"since it is impossible to explain the movements carried out
" by a machine, so long as we remain ignorant of the structure
" of its parts."

After pointing out the great difficulties which attend the
dissection of the brain and especially all attempts in such
tender structures to follow out the course and connections of
the strands of fibres and other parts, he delivers himself of
this pregnant passage :

"If indeed the white substance of which I am speaking
" be, as in most places it seems to be, wholly fibrous in nature,
" we must necessarily admit that the arrangement of its fibres
"is made according to some definite pattern on which doubtless
"depends the diversity of sensations and movements." Had
he who in the earlier half of the seventeenth century thus
foreshadowed the results of the last decades of the nineteenth
century, been led to devote to the problems of the brain the
same brilliant talents which had gathered in such valuable

x] of the Nervous System. 281

results in relation to glands and to muscle, the story of the
progress of physiology of the nervous system in the times
coming after him, would, we may well think, have been very
different from that which we have to record it actually is.
But it was not to be. Stensen as we have seen was drawn to
other things, and there was no one to take his place. Afber
Willis a long period followed before anyone took up again the
problems with which he had busied himself. Many valuable
additions continued, it is true, to be made to the anatomy of
the brain, slowly and from time to time ; but for a long while
no one took up the physiological inquiry with the fervour
which had marked the middle of the seventeenth century.
In tracing out the progress of science the trend of investi-
gation is found to vary from time to time ; at one period men's
minds are intently occupied with one set of problems, and at
another period these seem to be without cause almost wholly
neglected. But, even allowing for such an ill-understood
rhythm of inquiry, it is difficult to resist the thought that
the absence of research of which we are speaking was in part
at least due to the sterilizing influence of Stahl's animistic
doctrines.

During the eighteenth century, however, one remarkable
advancement of knowledge was made, which, though it con-
cerned not the fimctions of the brain proper, but the relations
of the functions of nerves to those of muscle, had a remarkable
influence over the whole of nervous physiology. This was the
chief work of the great Haller, and to this we must now turn.
In order, however, to appreciate the true value of Haller*s
labours it will be necessary even at the risk of some recapitu-
lation to pass in review the various views put forward from
time to time concerning the action of nerves, and the relation
of that action to muscular movement.

In an early lecture I spoke of Borelli's ideas concerning
muscular contraction and said a few words about his conception
of nervous action. I must now return to these, especially the
latter, and dwell upon some further details.

Borelli, as we saw, took a distinctly physical view of
nervous action. To him the animal spirits were known as a

282 The Older Doctrines [lect.

SUCCU8 nerveus, which he says "all recent authors admit is
" not a breath (flatus) or air, but has a liquid consistency like
"spirits of wine/* This succus nerveus is agitated in two
directions along the nerves, from the periphery to the brain as
when it serves to generate sensations, and from the brain to
the muscles as when it serves to give rise to movements. Acting
in the latter direction it, as Willis also taught, performs a
double function ; it not only causes visible movements by means
of the muscles, but also exercises a nutritive, plastic power by
which in all the tissues the crude material furnished by the
blood is fashioned into the living flesh.

He thus expounds the mechanical contrivance by which the
spirituous juice (the succus nerveus) can, along the same nervous
channels, be made to act both from without inwards, and from
within outwards.

" The nerve fibres are," he says, **by no means solid, full and
" impermeable, nor are they tubes hollow and empty like reeds,
" but are canals filled with a certain spongy material like elder-
" pith. Such a marrow of the fibres can easily be moistened by
" the spirituous juice of the brain, to which it is conjoined, and
" may indeed be saturated to turgescence, as we see sponges are
" saturated by water in contact with them."

He uses as an illustration a sheep's intestine filled not with
water only, but with sponge impregnated with water, in which
a concussion at one end is in a moment communicated right to
the other end.

" In the same way, if one of the extremities of the nerve
" fibre be compressed or pushed, or struck or pinched, forthwith
" the commotion and concussion or undulation ought to be com-
" municated right to the other end, because by reason of their
" contiguity, the parts lying first in an ordered series by pressing
"on those following, communicate the blow and the impulse
"right to the end.

" Hence it follows that the fibres or spongy ducts of certain
"nerves turgid with the spirituous juice can be shaken or
" pinched by that gentle motion of the spirits by which the acts
" of the command of the will are in the brain carried out, and
" then, by concussing the whole length of the nerve through the

x] of the Nervous System, 283

" convulsive irritation, can squeeze out and discharge from their
" extreme orifices some spirituous droplets into the appropriate
" muscle, whence the ebullition and explosion follow by which
" the muscle is contracted and rendered tense.

" And on the other hand when the extremities of the sensory
" nerves which end in the skin, nose, ears or eyes, are compressed
" or struck or titillated, it necessarily follows that forthwith the
"concussion, undulation, or titillation of the spirituous juice
"contained within the tubules is conveyed along the whole
"length of the nerve and reaches the particular part of the
*' brain to which the nerve fibres are joined. And here the
" faculty of the sensitive soul according to the region of the
" brain thus percussed, according to the vehemence of the blow
"and the fashion and mode of the motion, is able to form a
"judgment concerning the object causing the movement."

He expressly declares that the "juices, however spirituous
" and active, are always corporeal and cannot act at a distance,
"and cannot, without physical contact, increase, intensify, or
" depress the animal spirits ; it is by means of their corporeal
"presence that they either increase the animal spirits which
"are also corporeal, mixing themselves with them, or expel
" them, or transform them. Wherefore it cannot be conceived
" that nervous action can take place without some local move-
" ment of the nervous juice passing along the whole length of
" the nerve right to the brain."

Borelli's view of nervous action therefore was a strictly
physical one; in voluntary movement the concussion of the
nervous fluid started at the brain, and passing along the whole
length of the nerve, led to the ejection of some droplets of the
fluid into the substance of the muscle, and thus gave rise to
contraction. Of the act of contraction itself he was inclined to
take a chemical view, to believe that the inflation of a muscle,
which according to him was the essence of contraction, was
brought about "by something like a fermentation or an
"ebullition"; but of this he speaks guardedly.

Stensen, as we have seen, though he nowhere dwells on the
exact nature of nervous action or its relation to muscular con-
traction, had arrived at conceptions of the nature of muscular

284 The Older Doctrines [lect.

contraction itself, more true and exact than those even of
Borelli. He laid hold more clearly than Borelli seems to have
done of the truth that the contraction of a muscle is the
result of the contraction of the individual fibres ; and he quotes
the experiment that when a long muscle is cut up lengthways
by scissors in three or four bits, each bit may be made to
contract, as a proof that the power of contraction resides in the
muscular substance as substance and not in the whole muscle
as a machine. He further states that contraction is not de-
pendent on the action of arteries, or veins, or even necessarily
on that of nerves; and he insists that while all voluntary
movement is brought about by muscles, every movement which
a muscle carries out is not necessarily a voluntary one. He
ends his essay on muscle with the following remarkable
speculation :

" Concerning the fluid of muscles how uncertain, or i-ather
" how wholly wanting is our knowledge. Fluid certainly exists
"in the fibrillae of which the motor fibres are composed and
" between the fibrillae, also between the motor fibres themselves,
" in the membranous fibrillae *' (that is the connective tissue),
" and between the membranous fibrillae ; but in truth it is by
"no means clear whether these fluids are all of one kind or
"whether just as they are distinct in the seats which they
"occupy so they difier in material properties.

" Nor is it known whether any of these fluids are really like
" any one of the fluids so far known to us. Animal spirits, the
" more subtle part of the blood, the vapour of blood, and the
"juice of the nerves, these are names used by many, but they
" are mere words, meaning nothing. Some going further bring
"forward saline and sulphureous particles or something ana-
" logons to spirits of wine. Such things may perhaps be true,
" but are neither certain nor adequately distinct. Experience
" teaches us that a dose of spirits of wine restores exhausted
"powers, but who shall have determined whether that which
" restores the fluid spirit is to be ascribed to this said humour
" which we call spirit or to some other material or is joined to
" it through some other cause ?

" As the substance of this fluid is unknown to us, so is its

x] of the Nervous System. 285

" movement undetermined, since neither by sure reasoning nor
"by experiment has it been ascertained whience it comes,
"whither it tends, where on its departure it betakes itself.
« « « « «

"There remains another diflSculty of no less moment not
" yet cleared up, namely in what respect the movement of the
"fluid in a muscle while it is contracting differs from the
"movement of the fluid in the same muscle when it remains
"quiet, uncontracted. Is its quantity changed? or does it
" remain the same ? Is the fluid after the event, supposing it
" remains, the same as before the event ? Does the fluid move
" because the muscle contracts, or does the contraction of the
" solid proceed from the movement of the fluid ? "

This singular man had three hundred years ago pierced into
questions which are still moving us at the present day.

Since this is the last occasion which I shall have to speak of
Stensen, I may here venture to quote his appeal on behalf of
the value of science in practical matters :

"It may be shewn abundantly elsewhere how much medical
" practice owes to the anatomical experiments of this age, even
" if it were only for this that they have exposed the numerous
" errors which occur in the explanation of the causes of disease
" and at the same time shewn the reasons which have governed
"the application of remedies to be in most cases erroneous.
" To those who decry the value of science I would give as an
" answer this demand that they should ask their own consciences
" and see what solid basis there is for all those dogmas which
" they pronounce with such bold ease when they explain the
"symptoms of apoplexy, paralysis, convulsions, prostration of
" strength, syncope, and other diseases affecting animal move-
** ments, on what foundation they rest when they apply remedies
" for removing these evils, with the result that they do away
" not with the paralysis, not with the convulsion, but with the
" paralytic or the convulsed man.'*

Willis was very far from reaching the exact standpoint of
Borelli and Stensen; he explains muscular contraction in a
very different way. This is what he says:

" The animal spirits carried from the brain by the channels

286 The Older Doctrines [lbct.

" of the nerves to a muscle, caught up by the membranaceous
"fibrillai, and carried by means of these to the fibres of the
" tendon, are then plenteously stored up as it were in suitable
" storehouses. These spirits, being by nature exceedingly active
"and elastic, upon expanding as their power and opportunity
"permit, leap into the fleshy fibres, and presently afterwards,
" their impetus being exhausted, falling back, they retreat again
" into the tendons ; and this is repeated again and again. When
" however the animal spirits at the bidding of the instinct to
"bring about movement rush from the tendinous to the fleshy
"fibres, they there meet with active particles of a different
" nature supplied by the blood, and forthwith the two mixing,
" effervesce, so that out of the struggle and agitation of the
"two, the fleshy fibres, previously lax and porous, are stuffed
"full and thrown into corrugations, and all the fibres being
" thus corrugated at the same time, the contraction of the whole
" muscle is brought about. The contraction being finished, the
"pure spirits which remain for the most part retreat again
"into the tendinous fibres, the remaining particles being left
" among the fleshy fibres. The loss which has occurred among
" the latter is made good by the blood, that among the former
" by the nerves."

Mayow, as we have seen, had his own view about the matter
in question. He like many other discoverers who have laid hold
of a great truth, but have not had time to go all round it, was
inclined to see in his spiritus nitro-aereus, an explanation of
nearly all the unexplained phenomena of the universe ; he used
it to explain muscular contraction. This was in his view a
fermentation set up between the combustible, sulphurous
particles residing in the muscle, and the nitro-aereal spirit
brought to it by the nerves. But he got no further than
this.

While these several men of the seventeenth century whom
I have just mentioned were hovering about the truth of the
relation of nervous influences to muscular contraction, some
getting more, others less near, one among them, an English-
man, came upon the truth itself, and after him this part of
physiology stood still for near a hundred years. This was

x] of the Nervoibs System, 287

Francis Glisson, of whom I have already said something more
than once, but of whom I must now speak in more detail.

Bom in 1597 at Rampisham in Dorset of a good family,
Glisson entered in 1617 as a scholar at Gonville and Caius
College, Cambridge, where for a while he threw himself with
vigour and success into the usual learning of the place, taking
office in his college in 1624 as Fellow, in 1625 as Lecturer on
Greek, and in 1629 as Dean, though not in holy orders. Later
on, the publication of Harvey's work in 1628 being possibly the
determining cause, he turned his mind to medicine, and be-
coming in 1634 Doctor of Medicine was in 1636 appointed
Regius Professor of Physic. He appears to have carried out
his medical studies in London, for there is no evidence of
his ever having like Harvey gone abroad. Though for some
time he practised as a physician in Colchester, the greater
part of his life was passed in London, where he was very
active at the College of Physicians, of which he became Fellow
in 1635, and Reader in Anatomy in 1639. He was one of the
small band of men who used to meet in 1660 at Gresham
College to discuss natural knowledge, and who two years later
founded the Royal Society. He seems to have spent very little
time at Cambridge, treating his professional duties somewhat
lightly. Though he held his chair until his death, Dr Brady
being appointed his deputy in 1675, there is no evidence of his
ever having delivered any courses of lectures ; yet he appears to
have attended at Cambridge from time to time " to keep acts "
when candidates presented themselves for the degree of Doctor
of Medicine. In 1650 he petitioned the University for five
years' arrears of salary, apparently the years 1643-4 to 1648-9,
when, living at Colchester, he was wholly absent. Probably
life at Cambridge was distasteful to him ; the University was
very strongly Royalist, and Glisson was a pronounced Presby-
terian. While at Colchester he served as elder of the church
at the neighbouring village of Lexden ; and being shut up in
1648 in Colchester with the Royalists in the memorable siege
of that place, was chosen by the besieged authorities as a very
suitable member of the deputation sent forth to treat with
Fairfax on the terms of surrender. While in London he did

288 The Older Doctrines [lect.

his duties manfully during the great plague of 1665, was
President of the College of Physicians 1667-9, and passed
away at a ripe old age in 1677.

He was a good anatomist and a sound physician ; and he is
perhaps best known for his classic works on rickets and on the
liver. With the latter I have dealt in speaking of Malpighi.
Yet the work to which he gave most of his energy, and
the one which best illustrates the character of his mind, is
the Tractatus de natura substantice energetica, published in
1672 when he was an old man. For, accurate and careful
anatomist though he was, Glisson was essentially a philosopher,
steeped in all the old Aristotelian learning which he had
eagerly devoured in his youth, and striving to shape that old
learning into accordance with the new philosophy which was
fermenting around him. The Tractatus in fact is a bold
attempt to shew that all phenomena as well as of living things,
be they animal or vegetable, as of things not alive, are the
successive developments of the one fundamental energy of
nature. He says of this work in his preface, "It treats of
" Nature, well known by name but really understood by few,
" that Nature of which so many splendid things have been said
" by ancient as well as modem Philosophers. But the few who
"have so far recognized this life of nature have neither
"made clear its substantial origin in material things nor
"adequately distinguished it from vegetable or animal life.
" Still less have they, following up its more hidden traces, in-
" quired how it is developed from the natural into the vegetable
" and animal. Least of all have they shewn how the material
" soul, the vegetative soul and the sensitive soul arise out of
" the life of nature, though this is lifted up by successive steps."

He confesses that he has done no more than sketch out
the d priori proof of his view. The A posteriori proof has only
just been begun. That can not be supplied by an old man
like himself or indeed by the hands of any one man. " Let me
"hope that the Royal Society and other inquirers after truth
"will be moved to furnish it."

I call attention to this general view of Glisson's, because
this was the mother idea which led him to a special conception

x] of the Nervous System. 289

of the properties of muscular tissue, through which he antici-
pated modem teaching by nearly a hundred years. In his work
on the liver, in discussing how it comes about that the bile is
discharged into the intestines at certain times only, namely
when it is wanted, he shews that the gall-bladder and biliary
duct bring about a greater excretion when they are irritated.
And he argues that they cannot be irritated unless they possess
the power of being irritated. This power of being irritated he
proposes to denote by the term irritability. And he developes
this view again in his work on the stomach, De Ventriculo,
published the year of his death, though wholly written as early
as 1662, but laid aside in order that he might devote himself to
his work De Natura,

Thus it is undoubtedly to Glisson that we owe the first
introduction not only of the word but of the idea of ' irritability,'
which, revived by Haller, as we shall immediately see, in the
next century, became firmly established in physiology, and has
played an important part in the development both of physio-
logical and pathological views. Haller used the word in its
narrower sense as the property through which muscle responds
by movement to an external stimulus ; since then it has been
extended to mean response in any way, not by movement or
change of form only but by any kind of change, chemical
change, change of growth, and the like. And it is worthy of
note that Glisson from the very first used the word in its
widest sense, distinguishing the various ways in which irrita-
bility may be manifested and the various agents by which it
may be called forth.

It was perhaps by reason of the fundamental and highly
philosophic character of Glisson's conception that it did not
meet with immediate recognition. The idea had to be put
forth in the narrower form, which Haller gave to it, in order
to be understanded and accepted by physiological people.

Besides this introduction of the idea of irritability Glisson
made another contribution to muscular physiology of a wholly
different character, and yet one, from another point of view, of
fundamental importance. We have seen that Borelli, with all
his zeal for the exact mathematical treatment of physiological
p. L. 19

290 The Older Doctrines [lect.

problems, assumed, being led to do so by reasons of analogy,
without attempting to make any direct observations on the
matter, that a muscle during contraction was inflated, that
it suffered increase in bulk. Now Borelli took this view
although as we have seen he had freed himself from the
old, and to a large extent still current grosser conceptions of
the nature of the animal spirits. To those who held these
grosser conceptions the increase in bulk of a muscle during its
contraction was a natural and indeed necessary postulate ; the
animal spirits flowed into the muscle and made it swell up.
Such, with the admixture of certain new chemical conceptions,
was as we have seen the teaching of Willis.

All such ideas Glisson confronted with a single experiment,
the result of which deprived them of all solid basis. He gave,
and he was the first to give, the exact proof that when a
muscle contracts it does not increase in bulk ; and his old
experiment still stands in substance as the proof given in our
modern text-books. In his work De Ventriculo he says,

" But indeed this explosion and inflation of spirits has now
" for some time past been silenced, convicted by the following
*' experiment. Take an oblong glass tube of suitable capacity
"and shape. Fit into the top of its side near its mouth
" another small tube like a funnel. Let a strong muscular man
"insert into the mouth of the larger tube the whole of his
"bared arm, and secure the mouth of the tube all round to the
" humerus with bandages so that no water can escape from the
"tube. Then pour water through the funnel until the whole
" of the larger tube is completely filled, and some water rises
"up into the funnel. This being done, now tell the man
"alternately to contract powerfully and to relax the muscles
'*of his arm. It will be seen that when the muscles are
"contracted the water in the tube of the funnel sinks, rising
"again when relaxation takes place. From which it is clear
" that muscles are not inflated or swollen at the time that they
" are contracting, but on the contrary are lessened, shrunk, and
" subsided. For if they were inflated the water in the tubule
"so far from sinking would rise. From this therefore we may
" infer that the fibres are shortened by an intrinsic vital move-

x] of the Nervous System. 291

"ment and have no need of any abundant afflux of spirits,
" either animal or vital, by which they are inflated, and being
" so shortened carry out the movements ordered by the brain."

We nowadays avoid the concomitant changes in the volume
of blood present in the arm, and take not a whole limb of
man but the bloodless muscles of a frog; but otherwise the
plethysmographic proof we now use is identical with that of
Glisson.

But Glisson's irritability and his notable experiment were
like Mayow*s igneo-aereal spirit forgotten as the seventeenth
century passed into the eighteenth. We have to wait until the
middle of the latter century, when the truth was brought to
light again by the sagacious Haller in his views of nervous
action and its relation to muscular contraction. To these we
must now turn.

In his Elementay Haller in treating of the subject begins
by discussing the contractile force in general. "There is
"widely present not only in the animal but also in the
" vegetable kingdom a contractile force by which the elements
"of fibres are brought nearer to each other. This not only
"seems to be the cause of cohesion in general, but is
"rendered manifest by the fact that a fibre drawn out
"lengthways when let go very soon returns to its previous
"length, and never lays aside the effort to become shorter
"until it has so returned to its previous length." This
is more properly the elastic force. Besides this there is a
contractile force by which the tissues dead or alive shrink
when treated in various ways, when for instance they are
heated. A contractile force of such a kind is present in almost
all animal tissues, unless it be the very soft and pulpy ones like
brain or the very hard ones like bone and teeth. But there is
in addition a special contractile force proper to muscles alone.
"In a living animal, or in one only just dead there very
"frequently appears spontaneously in muscular tissue a swift
" vivid contractile movement by which the ends of the muscle
"are alternately brought nearer to the middle belly and then
"again recede from it." And even when this contractile
movement does not spontaneously appear, it may be excited if

19—2

292 The Older Doctrines [lbct.

a stimulus, such as pricking, or pinching, or some chemical
substance be applied.

Many writers consider this living contractile force as iden-
tical with the dead one just described as belonging more or less
to all tissues. This view Haller discusses and concludes, " that
" muscular fibre is the only one which is moved spontaneously
" in the living animal, or is brought by irritaments from rest to
"movement," and that "the living contractile force must be
" held to be distinct from the dead contractile force, since the
"two agree neither in the laws which govern them, nor in
"their duration, nor in their seat."

This force he calls the vis insita, the * inherent force,' and
the tissues possessing it he calls after Glisson * irritable.'

He then discusses whether this property of irritability is
identical with that of feeling, and concludes that it is not.
" There are many parts which feel but which are not irritable,
" and in particular a nerve, which is above everything sensitive,
" and yet possesses no contractile force except that common one
" found as stated above even in dead things.

" Wherefore this force since it is different both from mere
" elasticity and from that dead contraction which is common to
"all fibres, seems to constitute a peculiar property, proper to
" the muscular fibre, and indeed to mark the character of that
"fibre, so that every muscular fibre is irritable, and on the
" other hand you may fairly call muscular fibre everything that
" is irritable. It is however a force of its own kind, different
" from every other power, and to be classed among the sources
" of the production of motion the ultimate cause of which is
" unknown. This same force is inherent in the fibre itself and
" not brought to it from without."

He sums up thus :

"I (by my experiments published first in 1739, and again
"in 1743) separated this irritable nature on the one hand from
"a mere dead force, and on the other from the nervous force
" and from the power of the soul. I shewed that the move-
" ment of the heart and the irritable nature of the intestines
" depended on it alone. I confined it entirely to the muscular
" fibre, in which point the Batavian school does not agree with

x] of the Nervous System. 293

"me, but they will I hope do so when they are willing to
"distinguish the contractile force common to all animal fibre
"from the irritable force proper to muscle alone. I also
" shewed that that force was something perpetually living, and
"that it often broke out into movement though no external
" stimulus such as could be recognized by us was acting. By a
* * stimulus, however, it could at any time be called back fi:om
'rest into action. In a movement produced through it I
"distinguished between the stimulus which might be very
" slight, and the movement called forth by the stimulus which
"might be very powerful."

" Some," says he, " have wished to call this force the vital
" force, but this does not quite please me since the force may
" for some little time survive the life of the body. Hence I
"prefer to call it the force inherent in or proper to muscle."
He then goes on:

" Besides this force inherent in muscular fibre, another force
" is exercised in it, so far like the former in that it alone has its
"seat in muscular fibre. But it is different from the inherent
" force in as much as it comes from without and is carried to
" the muscles from the brain by the nerves, it is the power by
"which muscles are called into action." This he calls the
vis nervosa. It too survives the death of the body, and in
cold-blooded animals is of the same constancy as the inherent
force, so that in such an animal recently killed, in which no
sensation or voluntary movement remains, a muscle, provided it
be moist and whole, is thrown into convulsions when its nerve
is irritated. And the same is true of warm-blooded animals.

Having thus cleared the way by adopting the conception
that the movements of the body are the manifestations of
this inherent contractile power of muscle, the vis insita,
which may develop itself spontaneously, but which is usually
brought into play by the instrumentality of the nerves, by the
vis nervosa, Haller was able, in his remarkable chapter, "On
the Phenomena of the living Brain," to deal in a true scientific
spirit, indeed in a modern spirit, with the many and difficult
problems of the nervous system.

He first confines himself to what can be learnt fi:om

294 The Older Doctrines [lect.

experiment. " As the nature of the brain and of the nerves is
'' one and the same, so are these alike in function. In treating
" of them we will so far as possible make use of experiments, nor
'* will we at first at least go beyond the testimony of our senses."

Experiments and the testimony of the senses teach us, he
says, that nerves alone feel: only those parts which possess
nerves feel, and they feel through their nerves. The question
whether tendons feel presented diflSculties to him as it has
done to others after him ; but the main result of all his
experiments confirmed him in the view that nerves are the
only instruments of sensation, just as they by calling into
play the contractile power of muscles are the only instru-
ments of movement.

All the nerves are gathered together into the 'medulla
cerebri,' into the central parts of the brain ; whence it may be
inferred that " this central part of the brain feels and that in it
" are presented to the mind the impressions which the nerves
"disturbed at their extreme ends have carried to the brain."
This conclusion is supported by the phenomena of disease and
by the results of experiments on living animals. Sensation
manifests itself by movements, and when these central parts of
the brain are irritated by the knife or otherwise, the movements
which follow abundantly prove that sensation has been excited.
These movements are readily seen when the corpora striata,
the thalamus, the crura cerebri, the pons and the medulla
oblongata are injured. He goes on to argue that the cortex of
the brain must also feel, though no movement results when
it is irritated. "But the medulla of the corpora striata,
" or of the crura, or of the pons differs in no way from that of
" the rest of the brain except the actual cortex, and this unless
" it itself felt would be unable to bestow feeling on the medulla.
" If indeed the medulla is one and the same, and exactly alike
" at the summit and at the base of the brain, and if the deeper
" medulla obviously feels, it cannot with any right be said that
" the medulla placed in the higher situation, though possessing
" exactly the same nature, is destitute of feeling. The nerves
" therefore feel and carry to the brain the impressions of ex-
" temal objects. Those impressions are preserved in the brain.

x] of the Nervous JSystem. 295

" and after fifty or even after a hundred years, if a man lives so
"long, remain vivid and clear."

He then goes on to discuss the question whether any
particular parts of the brain, by a special privilege, function
as the seat of sensation and the source of movement. " In all
" cases we have shewn that the impressions of the senses are
" carried to the brain, and the cause of movement is conveyed
" thence through the nerves to the muscles of the whole body.
" But learned men, even those of the school of Galen as well
"as those of recent years, have suspected that the power of
" receiving feeling and of exciting movement was not alike in
" particular parts of the brain, and that the whole brain was
"not necessary for the full development of sensations.'* He
discusses this question, using as tests the phenomena of disease
and the results of experiments on animals. Guided by these,
he rejects the view held by Willis and others that the
corpora striata serve as the seat of sensation and the source of
movement, as well as the view that the cerebellum is essential
to life. In the light of our modern knowledge it is most
interesting to follow this physiologist of a hundred and fifty
years ago striving to find his way along the tangled path
presented by the nervous phenomena resulting from disease
or jfrom experimental interference.

He then passes on to what he calls 'conjectures.' The
views which he has " so far put forward have been based on the
" evidence of the senses, and if we have erred the error has lain
" in the experiment. This fault however can readily be mended
"since by simple repetition it can be ascertained whether we
" are really following nature's lead or have wandered from the
" truth, led astray by the fewness of the experiments or by some
" mistake in carrying them out. It is not equally easy to keep
" oneself from error in the matters which have now to be dis-
" cussed. Very little of what follows is based on the evidence of
"the senses, but is reached by probable arguments gathered
" from all manner of sources, and these while they are strong
" enough to furnish ourselves with the hope of truth, do not
" possess that certainty which will carry conviction to the mind
" of others."

296 The Older Doctrines [lect.

The first subject which he discusses, ' by conjectures/ is the
nature of nervous action. He expounds and rejects the view
put forward under various shapes that the nerves act as solid
bodies, after the fashion, for instance, of elastic strings along
which vibrations are conveyed. In his encyclopaedic manner
he recalls and discusses various views of this kind put forward
by various men, including that of Nicolas Robinson, who in
his work on the spleen supposed that the nerves of sense were
composed of little papillary machines, exceedingly small and
exceedingly numerous and minute, which struck by the object
giving rise to the sensation were thrown into oscillations and
so conveyed the impression to the mind.

He next discusses the view that nervous action depends
upon a fluid.

" All the ancients attributed to the nerves a most subtle and
"attenuated humour or rather fluid, for the word humour
" suggests something sluggish, to which they gave the name of
" spirits, and which, though invisible just like air, exercises a
" great power. This doctrine of the schools for many ages held
" its place ; lately, however, this doctrine of spirits, like all other
" things which pleased of old, began to totter. Then a sect
" by no means weak " (namely that of Stahl) " took up the posi-
"tion that the soul acted directly hand to hand in all the
''actions of the body and did not make use of instruments,
" by which it conveyed its commands to distant parts. People
"began to doubt very much about these spirits, and indeed
"now even the most distinguished men share these doubts."

He first marshals all that can be said against this hypo-
thesis of the spirits, that is of the active part of the nerve
being of the nature of a fluid, quoting among other things
the argument that a nerve .when ligatured does not swell,
and the like. But he finds these objections invalid; and
assuming therefore that the active nervous material is of
a fluid nature, he proceeds to discuss what must be its
essential characters. These lead him to the conclusion that
it cannot be of the nature of an albuminous solution, nor
spirituous in nature like alcohol, nor acid, nor sulphureous,
i.e. combustible. He likewise decides that it cannot be, as so

x] of the Nervous System., 297

many have thought, aerial. " At the close of the 17 th century,"
he says, "the name ether came into fashion, and it became
" the wont to attribute to it, to an invisible element which did
" not lend itself to experiment, everything the cause of which
"was unknown, light, gravity, magnetism. Some accordingly
" hold the spirits (the nervous fluid) to be of the nature of
*' ether or to be composed of ether." He rejects this also,
including in the rejection the view that the spirits consist of
electric material.

" Of what nature then," he asks, " is the material of these
" spirits ? " He answers, with the spirit of the eclectic philo-
sopher that he was, "an element of its own kind unlike
"everything else. An element, too subtle to be grasped by
"any of the senses, but more gross than fire, or ether or
"electric or magnetic matter, since it can be contained in
"channels and restrained by bonds and moreover is clearly
" produced out of and nourished by food. What forbids, since
"light is something different from fire, and the material of
"the magnet differs from both, and air and ether are unlike
" all the rest, what forbids that there should be this element of
" its own kind known to us only by its effects ? "

He then discusses as a speculation, but be it observed
as a speculation only, whether the nerves are hollow for the
conveyance of this nervous fluid ; he decides in the aflSrmative
and insists that by analogy the fibres of the brain must in like
manner be hollow also. He adds that the nervous fluid is
supplied and nourished by the arteries of the brain.

He rejects the view of there being two different kinds of
nervous fluid, one for the production of sensation and movement,
and another for the preservation of life, one connected with the
cerebrum, the other with the cerebellum. He rejects also the
view that there is one kind of nervous fluid for sensation and
another for movement; he sees no real diflSculty in the same
nerve serving both for sensation and movement.

Lastly, he passes to the most speculative question of all,
the 'seat of the soul.' He rejects the Stahlian opinion that
the soul and the sensorium commune is diflfused over the
whole body, present as well in the tip of the finger as in the

298 The Older Doctrines [leot.

brain. He recalls the results arrived at by experiment that
the medulla, the central part of the brain, is the seat of
sensation and the source of muscular movement. '*Nor in
"the cortex of the brain alone is the seat of sensation or
" the full origin of the cause of muscular movement ; each of
" these lies also in the medulla of the cerebrum and of the
"cerebellum." "This is not the place to speak about the
"soul, but the soul has nothing in common with the body
"other than sensation and movement. Now both sensation
"and movement have their source in the medulla of the
"brain. This therefore is the seat of the soul."

Asking the question whether the seat of the soul can be
defined within narrower limits, he remarks that "no narrower
"seat can be allotted to the soul than the conjoint origin of
" all the nerves ; nor can any structure be proposed as its seat
" except that to which we can trace all the nerves. For it will
" be easily understood that the sensorium commune ought to
" lack no feeling of any part of the whole animated body nor
"any nerve which can convey from any part of the body the
"impression of external objects. And the same may be said
" of the nerves of movement. Wherefore, even quite apart from
"the experimental results described above, we cannot admit
" as the exclusive seat of the soul, either the corpus callosum
" or the septum lucidum or the tiny pineal gland, or the corpora
" striata or any particular region of the brain/'

There remains still a somewhat different question whether
diflferent parts of the brain may not correspond to diflferent
functions of the soul. Some experiments and some of the
phenomena of disease do, he admits, give a certain support to
this, and the anatomical evidence points in the same direction ;
we may for instance suppose that the parts of the brain around
the entrance of the optic nerve are especially concerned in
vision, and the like. We may perhaps go a certain way in
this direction, but a very little way. " Our present knowledge
"does not permit us to speak with any show of truth about
** the more complicated functions of the mind or to assign in
"the brain to imagination its seat, to common sensation its
" seat, to memory its seat. Hypotheses of this kind have in

x] of the Nervous System. 299

" great numbers reigned in the writings of physiologists from
** all time. But all of them alike have been feeble, fleeting,
" and of a short life/'

Thus Haller wrote in the middle of the eighteenth century.
The nineteenth century has brought great gains to our know-
ledge of the nervous system. Charles Bell and Majendie laid
bare to us that fundamental distinction between sensory and
motor fibres which Haller failed to see. The hidden work of
the vaso-motor nerves, and of the other nerves which answer to
calls not those of the will, and which often play their parts in
silence without awakening consciousness, has been revealed to
us. The progress of physical and especially of electric science
has given us conceptions of how the pulses of sense and of the
will fly inwards and outwards along the nerve-fibres, concep-
tions clear and definite compared with Haller s dim gropings
after the nature of the nervous fluid. And above all in these
later years, the microscopical study, by refined methods, of
healthy and especially of diseased nervous structures, carried
out in concert with exact experiments on living animals
have gathered for us knowledge concerning those different
provinces of the brain which serve the different functions of the
mind — knowledge clear, definite, and founded on fact in place
of Haller s timorous conjectures, and have brought us within
measurable distance of being able to assign, not as feeble,
short-lived hypotheses, but as proved experimental results, to
sensation its seat, to memory its seat, and even to imagination
its seat. We have learnt much since Haller's time. But what
I have said of Haller justifies, I venture to think, the assertion
that we have gone forward so much because we have laboured
on Haller's lines. He expounded the nervous system in a spirit
which has become the modern spirit, and our progress has been
due to our following his example. And if he with the know-
ledge and the means at his command seems to us to-day often
to have walked haltingly or even often to have gone astray, we
may ask ourselves this question : Are not we, with all the know-
ledge and the means at our command, walking also haltingly,
if not more haltingly ; and are we not as often, if not more
often, going astray ? Shall we not seem so to those who tell

300 Doctrines of the Nervous System, [lbct. x

our story a hundred years to come ? For indeed it is one of
the lessons of the history of science that each age steps on
the shoulders of the ages which have gone before. The value
of each age is not its own, but is in part, in large part, a
debt to its forerunners. And this age of ours if, like its
predecessors, it can boast of something of which it is proud,
would, could it read the future, doubtless find also much of
which it would be ashamed.

A CHRONOLOGICAL TABLE OF THE CHIEF WRITERS
SPOKEN OF IN THE FOREGOING LECTURES.

Title and Date of Chief

Name

Birthplaoe

Birth

Death

physiological or anatomical Work

Mundlnns

Bologna

1326

De Anatome

1315

Berengarins, Jaoobas
(Carpi)

Guinterius, Johannes

Carpi

1470

1530

Commentaria

1521

Andemach

1487

1574

Institutiones Anatomi-
cae

1536

Paracelsus (Theophras-
tus von Hohenheim)

Einsiedeln

1490

1541

Chirurgia Magna

1536

Sylvius, Jacobus

Amiens

1478

1555

Commentarium

1539

Vesalius, Andreas

Brussels

1514

1564

Fabrica Humani
Corporis

1543

Servetns, Michael

Villanueva

1511

1553

Christianismi Besti-
tutio

1553

Columbus, Matheus
Bealdus

Cremona

1516

1659

De Be Anatomica

1559

Falloppius, Gabrielus

Modena

1523

1563

Observationes Anato-
micae

1561

Caesalpinus, Andreas

Arezzo

1519

1603

Quaestiones Peripate-
ticae

1671

Fabricius, Hieronymus

Aquapendente

1537

1619

De Venarum ostiolis

1674

Sanotorins, Sanctorins

Capo d'lstria

1561

1636

Statica Medica

1614

Aselli, Gaspar

Cremona

1626

De Lactibus

1627

Harvey, William

Folkestone

1578

1667

Exercitatio de Cordis
motu

1628

Van Helmont, Jean
Baptiste

Brussels

1577

1644

Ortus Medicinae

1648

Pecquet, Jean

Dieppe

1624

1674

Experimenta Nova
Anatomica

1661

Glisson, Francis

Bampisham

1597

1677

De Hepate

1654

Wharton, Thomas

Winston-on-Tees 1614

1673

Adenographia

1656

Willis, Thomas

Great Bedwyn

1621

1666

Cerebri Anatome

1669

Boyle, Robert

Lismore

1627

1691

New Experiments
physico-mechanical

1660

Malpighi, Marcello

Crevalcore

1628

1694

De Pulmonibus J

1661

Bellini, Lorenzo

Florence

1643

1703

De Stmctura Benum

1662

Descartes, Ben6

Tours

1596

1650

De Homine Liber

1662

302

Chronological Table.

Name

BirthplMe

Birth

Death

TiUe and Date of Chief

Stensen, Nicolans

Copenhagen

1638

1686

Observationes Anato-
micae

1662

SylyiuB, Francisoos

Hanover

1614

1672

Dispntationes

1663

De Graaf , Begner

Schoonhoven

1641

1673

De Natura et usn succi
pancreatici

1664

Hooke, Robert

Freshwater

1635

1703

Micrographia

1667

Mayow, John

London

1643

1679

De Sal Nitro &c.

1668

Lower, Biohard

Cornwall

1631

1690

Tractatus de Corde

1669

Peyer, Jean Conrad

Schaffhansen

1663

1712

De Glandulis Intesti-
norum

1677

Borelli, Giovanni
Alphonso

Naples

1608

1679

De Motu Animalium 1680-1

Bmnner, Jean Conrad

Diessenhofen

1663

1727

Experimenta nova
circa pancreas

1682

Stahl, Georg Ernest

Anspach

1660

1734

Theoria Medica

1708

Boerhaave, Hermann

Voorhout

1668

1738

Institutiones Medicae

1708

Beaomur, Ben^ Antoine
Ferchault

BooheUe

1683

1757

Snr la Digestion

1752

Black, Joseph

Bordeaux

1728

1799

De Humore Acido

1754

Haller, Albrecht

Bern

1708

1777

Elementa Physiologiae

1767

Priestley, Joseph

Fieldhead

1733

1804

Experiments and Ob- 1775-7
servations on differ-
ent Kinds of Air

Lavoisier

Paris

1743

1794

Snr la nature du prin-
dpe

1775

Scandiano

1729

1799

Dissertazioni di fisica

1783

animale e vegetabiie

INDEX.

Academy of Sciences, suppression of,

by the Convention. 254
Accademia del Cimento, 64

* Acini,' the, of Malpighi, 113, 114
Albinus, Frederick Bernard, Professor

of Anatomy at Leyden, 205
Alimentary canal, 48, 51

* Animism,' Stahl the founder of, 173
Arcfutus, the, 125, 127, 128, 132, 136,

139, 143, 167, 168
Artery-like vein, 13, 23, 28, 29, 33, 38,

40, 43, 59, 96
Aselli, Gaspar, the discoverer of the

lacteals, 48-51, 131, 138; * pancreas

of AseUi,* 60

Bacon, Francis, Novum Organon of,

130
Bassi, Laura, holds the Chair of

Mathematics at Bologna, 212
Beccher, Johann Joachim, the Physica

subterranea of, 167 ; Specimen

Beccherianum of Sylvius, 168
Bell, Charles, on sensory and motor

fibres, 299
Bellini, Laurentio, the Structura renum

of, 110; Professor of Anatomy at

Pisa, ib. ; physician to Cosimo III.,

Ill
Bentley, Biohard, establishes an

* elaboratory ' at Trinity College,

Cambridge, 231
Berengarius, Jacobus, dissection of

corpses by, 5 ; driven from Bologna

retires to Ferrara, ib.

Birds, Ben6 de Beaumur on the diges-
tion of, 210

Black, Joseph, Dissertatio de humore
acido a cibo orto of, 232 ; Professor
of Chemistry at Glasgow and
Edinburgh, ib.; experiments on
magnesia alba, Ac, ib.; the Treatise
of Chemistry of, 234-236

Bias, term used by van Helmont, 132,
136, 142

Boerhaave, Hermann, birth, 200;
early years at Leyden ; Doctor of
Philosophy ; of Medicine ; appointed
to the Chair of Medicine at Leyden,
201 ; death, 202 ; the Institutiones
medica of, 203 ; the Elements of
Chemistry of, 227

Borelli, Giovanni Alphonso, birth, 62 ;
studies mathematics at Bome;
accepts the Chair of Mathematics
at Messina; goes to Florence to
hear Galileo; returns to Messina;
publishes his first work, an account
of the Pestilence in Sicily; accepts
the Chair of Mathematics at Pisa ;
a self-taught man, ib. ; friend-
ship with Malpighi; becomes es-
tranged from him; publication of
his Euclides restitutttSf 64; De vi
percussionis ; at work at the De
motu animalium, 65; publishes his
treatise on * The natural movements
depending on gravity'; leaves Pisa
and returns to Messina; goes into
exile at Bome ; investigates an

304

Index.

eruption of Etna; Christina,
daughter of Gnstavns Adolphns,
takes him under her protection, 65,
66; dedicates his work on animal
motion to her; robbed by his
servant; takes up his abode
among the Society of the Scholsd
Pisd of San Pantaleone; death,
66; publication of De motu ani-
malium, 67 ; account of the book,
67-69; on muscular contraction,
69-76; on the circulation, 76-80;
on the structure of glands, 80-82 ;
on the secretion of urine, 82 ; on
the physiology of nerves, 82, 83;
makes the friendship of Malpighi at
Pisa, 88; his character contrasted
with that of Malpighi, 88, 89;
contrasted with Franc. Sylvius,
160, 161 ; on gastric digestion, 165,
166; on respiration, 177-179; on
muscular contraction and nervous
action, 281-283

Bossuet, J. B., endeavours to convert
Stensen to the Catholic religion,
106

Boyle, Hon. Bobert, pneumatic machine
of, 178, 179

Brunner, J. C. von, birth ; graduates
at Strassburg; occupies the Chair
of Medicine in Heidelberg ; Court
Physician at Dusseldorf; death,
162; publishes Experimenta nova
circa pancreas; and Dissertatio
de glandulis duodeni; Brunner's
glands, 163; experiment on the
removal of the spleen and pancreas,
163, 164

Caesalpinus, Andreas, birth ; Professor
of Medicine at Pisa; Professor at
the Sapienza University ; Physician
to Pope Clement VHI., 31 ; passion
for theology ; opposes Galen, 32 ;
the QiuBstiones peripateticce and
Qtuestiones Mediae of, 32-36;
credit of Harvey's work claimed
for, 63

Calcar, J. S., illustrates the works of
Vesalius, 10

Cannanus, J. B., observes the valves of
the veins, 36

Capillaries, 98, 100

Carminati, on the acidity of gastric
juice, 222, 223

Carpi, V. Berengarius

Castello, Benedetto, Borelli's teacher
at Bome, 63

Castello, P., death of, 90

Cavendish, experiments on factitious
air, 260

Charles V., the father of Vesalius
apothecary to, 6 ; Vesalius dedicates
his * Structure of the human body *
to, 10; appoints Vesalius Court
Physician, 16

Chemical Laboratory, the first Uni-
versity, 147

Christina, daughter of Gustavus
Adolphus, takes Borelli under her
protection at Bome, 66, 66

Church, The, and Science, 3-6, 17

Cimento, Accademia del, 64

Circulation of the blood, 69-61, 76-80,
148, 224-227

Columbus, Matheus Bealdus, deputy
of Vesalius at Padua, 16 ; appointed
Professor of Anatomy at the Uni-
versity of Pisa, 26 ; birth ; studies
at Venice and Padua ; acknowledge-
ments to Lonigo; estrangement
with Vesalius ; nominated to the
Chair of Surgery in Padua, 26 ; nomi-
nation unconfirmed; withdraws to
Pisa; teaches anatomy there; called
to the Chair of Anatomy in the Uni-
versity of Bome ; death, 27 ; the De
Re Anatomica of, 27-31 ; an imitation
of Vesalius, 27 ; his teaching of the
pulmonary circulation identical with ^
that of Servetus, 30; credit of
Harvey's work claimed for, 63

Consentinus, T. C, story of, concerning
Sarpi and Harvey, 64

Convention, suppression of the Aca-
demy of Sciences by the, 264

Index.

305

* CorxM aTuitomieys,^ the, at Bologna,

87
Gosimo III., Stensen made Court

Physician to, 106 ; Laurentio Bellini

physician to, 111
Costaens, Joh., on the mesaraic veins,

49
Grahbe, Isabella, maiden name of the

mother of Yesalius, 6
Crawford, Adair, publishes a * Theory

of Heat,' 248
Curio, a learned doctor at Padua, copy

of the theological work of Servetus

sent to, 24, 30

Dephlogisticated air, 240

Descartes, Ben6, birth and death, 57 ;
Theory of the Universe; Discours
de la m^thode ; De homine ; Des-
cartes the Herbert Spencer of
the age ; not convinced by Har-
vey's arguments, 68 ; on the
circulation, 69-61; N. Stensen on
the position of, as a physiologist,
62 ; the * rational soul ' of, 260 ; his
exposition of the working of the
body as an earthly machine, 261-
269

Digestion, 166, 166, 171, 172, 207,
213, 220-223

Digestions, the six, of van Helmont,
136-141

Drebbel, Cornelius, the maker of an
improved microscope, 86

Dubois, Fran<^is, v. Sylvius, Fran-
ciscus

Du Bois, J., V. Sylvius, Jacobus

Duct, Stensen's discovery of the
parotid, 106, 108, 109

Ductus aquosi and serosi, 61

Edwards, W. F., *the influence of
physical agents on life,' 263

* Elements,' the two, of van Helmont,

132 ; the three, of Valentine, 125,
127
Embryology, Malpighi the founder of
the science of, 93

P. L.

Ent, Apologia of, 64
Erasistratus, 48, 84
Etna, Mount, Borelli's investigation

of an eruption of, 66
Eustachian tube and valve, 48

Fabricius, Hieronymus, birth, 36 ;
studies under Falloppius at Padua ;
succeeds him; death of, 36; the
De venarum ostiolis of, 36, 37 ; the
De respiratione et ejus instrumentis
of, 38, 39 ; on the formation of the
foetus, 40

Falloppius, Gabr., anatomical obser-
vations of, 18, 26, 26; Vesalius's
'Examen' of, 18, 19; succeeds
Vesalius at Padua; birth ; Fallop-
pian canal and Falloppian tubes,
26

Ferdinand II., Grand Duke of Tuscany,
offers the Chair of Theoretical
Medicine at Pisa to Malpighi, 88;
Stensen made Court Physician to,
106

Fermentation, 160-162, 171, 172, 176,
216, 221

Ferrein, Ant., the pyramids of, 117

Fixed air, 246

Fontana, invention of the compound
microscope attributed to, 86

Fracastorius, on the motion of the
heart, 43

Fugger family, mines in the Tyrol
held by the, 124

Galen, structure and use of the parts
of the body of man, 3 ; main outlines
of the physiology of, 12

Galileo Galilei, leaves Pisa and be-
comes Professor at Padua, 57 ; effects
of the teaching of, on the problems
of physiology, 62 ; death of, 63 ;
invention of the compound micro-
scope attributed to, 86

Gas, term used by van Helmont, 132,
134, 136, 142

Glands and tissues, 101-120

Glands, Borelli on the structure of,

20

306

Index.

80-82 ; discovery of new, by Peyer,
162

GUnber'8 salt, 148

Glisson, Francis, sketch of the mor-
phological constitution of the animal
body, 86, 86; on the liver, 111, 112;
birth and education: Fellow of
Gonville and Gains College; ap-
pointed Regius Professor of Physic;
Fellow of the Royal College of
Physicians, 287 ; at work in London
during the Plague, 288; his Trac-
tatui de natura substantice tnergetiea,
288, 289; on the Uver, 289; the
stomach, 289, 290

Graaf, Begner de, birth; studies under
Sylvius at Leyden ; practises at
Delft; dies there, 153; on pancreatic
juice, 164-157

Grew, Nehemiah, * the Anatomy of
Vegetables begun,' 92

Guinterius, Joh., Yesalius a pupil
of, 7

Giinther, Joh., v. Guinterius, Joh.

Hales, Stephen, birth, education, and
death; makes the acquaintance of
Horace Walpole, 231; 'Statical
Essays ' of, 231, 232

Haller, Albrecht von, publication of
Vol. I. of his Elementa Physiologia ;
birth and education, 205; accepts
the Chair of Anatomy, Botany,
and Medicine at Gottingen; retires
to Bern; completes his Elementa;
death, 206; his exposition of diges-
tion, 207, 208; bile, 208, 209; on
the pancreas, 209; on respiration,
228-230; on nervous action, 291-
297; on the 'seat of the soul,'
297-299

Harvey, William, birth; at Cambridge;
leaves England for Padua, 41 ; degree
at Padua; return to England; in
London; Physician to St Bartho-
lomew's Hospital ; Physician to King
Charles I. ; in charge of the Princes
at the battle of Edgehill; retires

into private life; publishes the De
generatione animalium; death, 42;
on the circulation of the blood, 42-
48, 52-64 ; on the lacteal veins dis-
covered by Aselli, 52; the credit of
his work claimed for others, 53 ; his
method strictly physiological, 55

Hassenfratz, on the combination of
oxygen with the carbon and hydro-
gen of the blood, 252

Heat, 248

Helmont, J. B. van, birth; studies
at Louvain, 128; refuses the M.A.
degree; takes his Doctorship of
Medicine ; travels ; his return
and marriage; life and death at
Vilvorde, 129; the Ortus Medicirus
of; De magnetica vulnerum cura-
tionej 130; influence of Para-
celsus on him; comparison of the
two intellects, 131; Gas and Bias,
terms used by him, 131-136; the
six digestions of, 136-141 ; the sen-
sitive and motive soul of, 260

Herbst, J., v. Oporinus, J.

Hippocrates, 4, 229

Histology, 94

Hofmann, J. M., claims the discovery
of the duct of the pancreas, 104

Hohenheim, Theophrastus von, v,
Paracelsus

Hooke, Robert, new ideas started by,
under the use of the microscope, 86 ;
birth and death of; curator of ex-
periments to the Royal Society; the
Micrographia of, 180; experiment
on artificial respiration, 180, 181

Horn, van, on the discovery of the
thoracic duct, 60, 51

Hunter, John, on digestion, 220-223 ;
accuses Reaumur of 'anatomical
ignorance'; criticizes Spallanzani;
the latter's reply, 220

Hydrocarbonous fluid, 252, 263

Hydrogen, 250, 261

Ingrassias, John Philipp, the stapes
first observed and described by;

Index.

307

Buoceeds Vesalios as physician to

PhiUp II., 31
Innocent XII. appoints Malpighi his

physician, 119
Irritability, 289, 292

Janssen, Hans and Zacharias, the
supposed inventors of the micro-
scope, 86

Jolive, takes degree at Cambridge ; on
lymphatics, 51

Kidneys, functions of the, 102

Lacteals, 48-51, 131, 138, 157
Lagrange, on respiration, 252
Laplace, Memoir on Heat, 248
Laudanum, use of, said to be due to

Paracelsus, 127
Lavoisier, Ant. Laurent, birth and
education; admitted to the Aca-
demy of Sciences; publication
of his work *0n the nature of
the principle which combines with
metals during their calcination,'
244 ; the discoverer of oxygen ; on
* General considerations concerning
the nature of acids,' 245 ; on animal
respiration, 245-248; publishes in
conjunction with Laplace, Memoir
on Heat, 248; publishes in con-
junction with Sequin *The transpi-
ration of animals,' 251 ; his theory
of a hydrocarbonous secretion over-
thrown by Spallanzani, 253; arrested
and executed by the Convention,
254
Leeuenhoek, Anton van, new ideas
started by, with the aid of the
microscope, 86; observes the capil-
laries, 98; description of red blood
corpuscles by, 100
Liver, functions of the, 102
Lower, Bichard, experiments on trans-
fusion, 181, 182 ; practises in London ;
publishes the Tractatus de cordey
182; the instructor of Thomas
Willis, 270

Loyola, Ignatius, contemporary with

Vesalius, 8
Lung, discovery of the structure of,

by Malpighi, 90, 95
Luzzi, B. de', v. Mundinus, B.
Lymphatics, 61, 62, 106, 157

Magnus, Gustav, on respiration, 253,
254

Malpighi, Marcello, new ideas started
by, with the aid of the microscope ;
birth; student at Bologna, 86;
disputes with the Sbaraglia family ;
joins the Corua anatomicus at Bo-
logna ; becomes Doctor in Medicine
and Philosophy; in disfavour with
the Obscurantists ; marries the sister
of Massari, 87; made Professor of
Medicine; accepts the Chair of
Theoretical Medicine at Pisa; makes
the friendship of Borelli there ; his
character contrasted with that of
Borelli, 88, 89; his manuscript of
a Dialogue between a Galenist and a
surgeon accidentally burnt; resigns
his Chair at Pisa and returns to
Bologna as Professor of Medicine;
discovers the structure of the lung ;
accepts the Chair of Medicine at
Messina, 90; makes friends with
Stensen; accepts post again at Bo-
logna, 91 ; invited to a philosophic
correspondence with the Boyal
Society of London ; his works pub-
hshed by the Society; his book on
the anatomy of plants, 92; the
founder of the science of embryo-
logy; devotes himself to the study
of the silkworm, 93 ; the first histo-
logist, 94 ; his work * On the Lungs,'
95-98; further discovery touching
the blood, 99; work of, on the
tongue and external organ of sense,
100, 101; on the anatomy of the
brain, 101; glands, 101-104; on the
liver, 112-116; the kidney, 116,
117; the spleen, 117, 118; treatises
written at Bologna, 118; becomes

308

Index.

physician to Innocent XII., 119;
death, 120; autobiography; Borelli's
criticism of his views on respira-
tion, 177; on the histology of the
nervous system, 269

Malpighian layer, 100

Maria Theresa, Empress, offers the
Chair of Natural History at Pavia
to Lazaro Spallanzani, 212

Massari, Bartolommeo, forms a club
called the Corxis anatomicus at
Bologna, 87; sudden death of,
88

Mayow, John, at Oxford; publications
of; admitted Fellow of the Boyal
Society; death, 185; on respiration,
185, 186, 192; tract on sal-nitrum,
186; on combustion, 189, 190; iden-
tification of burning and breathing,
190-198; on muscular contraction,
286

Medici, Cosimo de', 16; appoints
Columbus Professor of Anatomy at
Pisa, 26

Medulla cerebri, 294

Mesaraic veins, 49

Microscope, 70, 84, 86, 94, 96, 97

Motor fibres, 299

Mundinus, B., teaches at Bologna;
the Anatomia of, 4

Muscular contraction, 69-75

Nerves, physiology of, on Borelli's

views, 82, 83
Nervous system, Vesalius on the,

255-257 ; Malpighi on the histology

of, 269
Nitrogen, discovery of, 236

Oporinus, J., printer of the Fabrica
kumani corporis of Vesalius, 3

Oxygen, prepared by Priestley, 240;
discovered by Lavoisier, 244, 246

Pancreas, 50, 209; removal of the,

163, 164
Pancreas, discovery of the duct of the,

104

Pancreatic juice, 154-157

Paracelsus, why so called, 123, 124;
enters the University of Basel; be-
comes the pupil of Bishop Trithemius
at Wiirzburg; spends some time in
the mines in the Tyrol, 124; learns
the doctrines of Valentine from
Bishop Trithemius, 125; settles at
Basel; driven hence, 126; dies at
Salzburg; use of laudanum said
to be due to him, 127; his doc-
trines taken up by van Helmont,
128

Parotid duct, Stensen's discovery of
the, 106, 108, 109

Pecquet, Jean, Experimenta nova ana-
tomica of, 50

Peyer, Jean Conrad, the Exerdtatio
anatomica medica de glandulis intes-
tinorum of, 162

Philip n., Vesalius Court Physician
to, 17

Phlogiston, 167, 189, 224, 226, 233,
239, 241

Plants, anatomy of, Malpighi's work
on the, 92

Priestley, Joseph, oxygen prepared by,
240 ; on respiration, 237-243

Pulmonary artery, v. Artery-like vein

Putrefaction, 216

Reaumur, Ben6 Antoine Ferchault de,
birth, etc.; his thermometer; his
work on insects; on the diges-
tion of birds, 210; accused of
* anatomical ignorance' by Hunter,
220

Respiration, 175, 180, 181, 228-230,
237-248

Rhazes, the ninth book of, translated
by Vesalius, 8

Robinson, Nicolas, on the spleen,
296

Royal Society of London, founding of
the, 174; Malpighi invited by the
Society to a philosophic conference ;
the Society publishes his works,
92

Index.

309

Budbeok, Olaus, Nova exercitatio

anatomica of, 51
Buffo, Visconte, the friend and patron

of Malpighi, 92
Buini, Carlo, on the anatomy of the

horse, 53
Bujsch, on the distribntion of the renal

blood vessels, 117

Sagrino, 96, 97

Salts, study of, 148

Sanctorius, S., birth ; studies at Padua ;
practises at Venice; Professor of
Theoretical Medicine at Padua;
dies in Venice, 145; publication of
his Medical Statics ^ 145; account
of the book, 146

Sarpi, Petrus Paulus, studies anatomy
under Fabricius, 53, 54 ; the story of
his arrival at conclusions similar to
those of Harvey; said by Ent to
have made use of Harvey's book
as his own, 54

Sbaraglia family disputes with the
Malpighi family, 87

Sensory and motor fibres, 209

Septalius, Senator, 49

Servetus, Michael, birth; studies at
Paris under Giinther and Sylvius;
physician to Abp of Vienna; theo-
logical works of; he and his works
burnt by order of Calvin, 22; credit
of Harvey's work claimed for, 53

Silkworm, 93

Soul, the, 142-144, 168-171, 220, 269,
260, 271, 272, 297-299

Spallanzani, Lazaro, birth and
education ; studies under Laura
Bassi; Professor at Beggio and
Modena; offered Professorships at
Pa via and Padua which he refuses ;
death, 212; his works on reproduc-
tion, etc., 213; contributions to the
physiology of digestion, 213-216;
on fermentation, 216; on gastric
juice, 218, 219; criticism of, by
Hunter, 220 ; on the respiration of
animals, 253

Spu-its, 12, 13, 23, 47, 63, 56, 56, 60,
136, 139, 141, 197, 260, 274-277.
284, 286

Spleen, removal of the, 163, 164

Stahl, G. E., Court Physician at
Weimar; Professor of Medicine at
Halle; Physician to King of Prussia,
167 ; the * sensitive soul' of, 168-171 ;
his treatise De mixti et vivi corporis
vera diversitate, 169; what his
teaching briefly was, 172, 173; on
the circulation of the blood, 224-227

Stapes, the, 31

Stelluti, Francisco, the first to use the
microscope at Bome, 86

Stensen, Nicolaus, on the position of
Descartes as a physiologist, 62;
the De musculis observationum sped-
merif and Elementorum myologia
specimen of, 70, 71; makes the
friendship of Malpighi, 91 ; dis-
covery of the parotid duct; the
Observationes Anatomica of; at-
tracts attention of Bossuet; dis-
course on the anatomy of the brain;
made Court Physician to Ferdinand
n. ; and Cosimo III., 106 ; his
work called De solido intra soli-
dum; forsakes his old studies and
devotes himself to religion, 107;
receives the titulary honour of
Bishop of Titiopolis; teaches ana-
tomy at Copenhagen, 108; describes
his discovery of the parotid duct,
108-110; on muscle, 284; on the
value of science in practical matters,
286

Stevens, of Edinburgh, experiments
on digestion, 219, 220

Stone in the bladder, 233

Swammerdam, Joh., new ideas started
by, with the aid of the microscope,
86; the Biblia Natura of, 99, 100

Sylvius, Franciscus, studies at Sedan
and Basel; Professor of Medicine
at Leyden; has a * Laboratorium '
built for him there, 147; devotes
himself to the study of salts ; writes

310

Index.

on the oircnlation; a follower of
Harvey; Harveian doctrines esta-
blished in Holland through the
advocacy o^ 148; what Stensen
says of Sylvins, 149; his idea of
fermentation, 150; of bile, 157,
158 ; on the secretion of nrine, 159 ;
his view of the spleen, 160; Sylvins
contrasted with Borelli, 160, 161;
Specimen Beccherianum of, 168 ; on
respiration, 186
Sylvias, Jacobns, teaches anatomy at
Paris; succeeds Vidns Vidins at
the Ck>llege of France ; * fissure *
of; a strict Galenist; influence of,
5 ; his teaching overturned by
Vesalius, 6

Tadinus, Alexander, 49
Thoracic duct, 50, 51
Tiepolo, Venetian ambassador, 18, 19
Torricellian vacuum, 178
Transfusion, experiments on, 181,182
Trithemius, Bishop, the teacher of
Paracelsus, 124, 125

Urine, Borelli on the secretion of, 82 ;
F. Sylvius on the secretion of, 159

Valentine, Basil, the Currus trium-
phalis antimonii of, 124; the three
* elements' of, 125, 127

Vasa aquosa and serosa, 51

Vein-like artery, 13, 23, 28, 33, 38,
43, 59, 96, 175

Veins, valves of the, observed by
Gannanus, 36

Vena cava, 43, 44, 45, 47

Vena porta, 48

Vesalius, Andreas, Fabrica humani
corporis of, published, 3; birth;
studies at Louvain; at Paris
under Sylvius, 6; a pupil of
Guinterius; back at Louvain, 7;
translates the ninth book of Bhazes

and goes to Venice, 8; honours
and teaching at Padua, 9, 10;
publication of 'Structure of the
human body'; Anatomical tables;
editions of Guinterius and Galen;
treatise on blood letting, 10 ; leaves
Padua; reviled by Sylvius and
others during his absence; return
to Padua, 15 ; discouraged by op-
position, 16 ; bums all his mss. ;
accepts the post of Court Physician
to Charles V., 16; afterwards to
Philip XL, 17; marriage, 16; *Ex-
amen' of the anatomical observa-
tions of Falloppius, 18; decides
on a pilgrimage to Jerusalem ;
death at Zante ; his influence on
science, 19; the forerunner of
Harvey, 20; his work a necessary
preparation for Harvey's labours,
55 ; views of, on the nerVous system,
255-257 ; on vivisection, 257, 258 ;
on the brain, 258, 259; the chief
soul, 259

Vidius, Vidus, at the College of France,
5

Vieussens, on fermentation, 150-152

Vis insita of Haller, 292, 293

Vital principle, 220

Walpole, Horace, 231

Wedel, on the archaeus, 167

Wesalius, t;. Vesalius

Wharton, Thomas, on glands, 105

Willis, Thomas, birth and educa-
tion; made Sedleian Professor at
Oxford, 269 ; on the structure and
functions of the brain, 270-279 ;
criticized by Mayow and Stensen,
279, 280 ; on muscular contraction,
285, 286

Wirsung, J. G., discovery of the duct of
the pancreas by ; tragic death of, 104

Witing, original name of the family
of Vesalius, 6

CAHBBIDOE: PBINTBD BY J. AND C. F. CLAY, AT THE UNFTEBSITY PBESS.

CAMBRIDGE BIOLOGICAL
SERIES

The Elements of Botany, By Francis Darwin, ScD.,
M.B., F.R.S., Fellow of Christ's College. Second edition. Crown
8vo. With 94 illustrations. 4^. 6^.

journal of Education. A noteworthy addition to our botanical
literature.

Practical Physiology of Plants. By Francis Darwin,
Sc.D., F.R.S., and E. Hamilton Acton, M.A. Third edition.
Crown 8vo. With 45 illustrations. 4J. 6</.

Nature, The authors are much to be congratulated on their work,
which fills a serious gap in the botanical literature of this country.

Morphology and Anthropology. By W. L. H.
Duckworth, M.A., M.D., Fellow and Lecturer of Jesus Collide,
University Lecturer in Physical Anthropology. Demy 8vo. With 333
illustrations. 15J. net.

Athenceum. Mr Duckworth has managed to produce in his "Mor-
phology and Anthropology" just such a text-book as students have long
been asking for.... It is no easy task to have undertaken such a work and
the author is to be congratulated on the success which has attended his
efforts. The volume can be confidently recommended to all whose studies
lead them in this direction.

Lectures on the History of Physiology during the

Sixteenth, Seventeenth and Eighteenth Centuries. By Sir M. Foster,
K.C.B., M.D., D.C.L. Demy 8vo. With a firontispiece. 9^.

Nature, There is no more fascinating chapter in the history of science
than that which deals with physiology, but a concise and at the same time
compendious account of the early history of the subject has never before
been presented to the English reader. Physiologists therefore owe a debt
of gratitude to Sir Michael Foster for supplying a want which was widely
felt.... No higher praise can be given to the book than to say that it is
worthy of the reputation of its author.

The Soluble Ferments and Fermentation, By J.
Reynolds Green, Sc.D., F.R.S., Professor of Botany to the
Pharmaceutical Society of Great Britain. Second edition. Demy

8V0. I2X.

Nature, It is not necessary to recommend the perusal of the book to
all interested in the subject since it is indispensable to them, and we will
merely conclude by congratulating the Cambridge University Press on
having added to their admirable series of Natural Science Manuals an
eminently successfiil work on so important and difficult a theme, and the
author on having written a treatise cleverly conceived, industriously and
ably worked out, and on the whole, well written.

lOOO

7.12

Cambridge Biological Series

Conditions of Life in the Sea. A short account of
Quantitative Marine Biological Research. By James Johnstone,
Fisheries Laboratory, University of Liverpool. Demy 8vo. With a
chart and 31 illustrations. 9^. tut.

The Natural History of some Common Animals.
By Oswald H. Latter, M.A., Senior Science Master at Charter-
house. Crown 8vo. With 54 illustrations. 55. net,

. Nature, An excellent book, written by a man who is equally in his
element whether he writes as an outdoor naturalist or as a laboratory
student. This combination is by no means a common one, and it is just
the combination that is wanted for a book of this kind.... Altogether the
book is an admirable one.

Athenaum, A book that may be judiciously placed in the hands of
any boy who evinces a reasonable interest in the animal life around him.

The Classification of Flowering Plants. By Alfred
Barton Rendle, M.A. (Cantab.), D.Sc. (Lond.), F.L.S., Keeper
of the Department of Botany, British Museum. Vol. I. Gymno-
sperms and Monocotyledons. Demy 8vo. With 187 illustrations,
lar. 6d, net.

Gardener's Chronicle, Numerous illustrations and an excellent index
add to the value of the work. We heartily congratulate the author on the
partial accomplishment of a difficult and laborious task. The part before
us does but whet our appetite for what is to follow.

Athenceum, The first instalment of a text book which will well
represent the state of our knowledge in the early years of the century.
In the present volume the Gymnosperms and the Monocotyledons alone
are dealt with ; but they are treated vrith such excellent co-ordination of
detail and such clear-headed sense of proportion, that we eagerly await
the publication of the next instalment.

The Origin and Influence of the Thorough-bred

Horse. By W. Ridgeway, Sc.D., F.B.A., Disney Professor of
Archaeology and Fellow of Gonville and Caius College. Demy 8vo.
With 143 illustrations, xis, 6d, net.

Westminster Gazette, There has never been a more learned contribution
to equine literature than Professor Ridgeway's comprehensive and exhaustive
book.

Spectator. It would be difficult for Professor Ridgeway to write a book
which did not contain at least one wholly novel thesis, and the present work
is no exception to his practice. It is also an encyclopaedia of information
on the history of the Equidae, collected from every source, from post-
Pleiocene deposits to modem sporting newsf)apers. No detail escapes the
author's industry, and... the result is a monument of sound learning, unique
of its kind.

Manual of Practical Morbid Anatomy, being a Hand-
book for the Post-mortem Room. By H. D. Rolleston, M.A.,
M.D., F.R.C.P., and A. A. Kanthack, M.D., M.R.C.P. Crown
8vo. 6s,

Cambridge Biological Series
Fossil Plants : a text-book for students of Botany

and Geology. By A. C. Seward, M.A., F.R.S., Professor of
Botany in the University of Cambridge. In 3 vols. Demy 8vo.
Vol. I. with a frontispiece and 11 1 illustrations. lor. net. Vol. II.
with a frontispiece and 265 illustrations. 15X. neU

[Vol. Ill in the Press.

Revue Scientifique, Nous ne pouvons entrer dans le detail ; mais il est
Evident que M. Seward, praticien distingu^ lui-m6me, est tr^s au courant
des travaux des autres, il les cite et utilise abondamment ; et ceci est fait
pour inspirer confiance. Au total, son oeuvre est appuyee sur des bases
solides, et elle restera sans doute longtemps le br^viaire, le manuel de ceux
qui veulent, non pas seulement sHnitier k la pal^obotanique, mais retrouver
les renseignements qui sont ^pars dans des centaines de monographies qu'on
a souvent peine k se procurer. Le livre de M. Seward fait partie des
Cambridge Natural Science Manuals, et il est digne de cette collection, qui
est elle-m6me digne du foyer scientifique universellement repute, oii il a vu
le jour.

Zoology. An Elementary Text- Book. By A. E.

Shipley, Sc.D., F.R.S., and E. W. MacBride, M.A. (Cantab.),
D.Sc. (London). Second edition. Demy 8vo. Witi 349 illustrations.
I or. 6d, net.

Pall Mall Gazette, Precisely the sort of book which, if it came into a
thoughtful boy's hands, would turn him from a smatterer into a student. ...
One of the most instructive and attractive books that could be put into the
hands of a young naturalist.

Trees : A Handbook of Forest Botany for the Woodlands
and the Laboratory. By H. Marshall Ward, Sc.D., F.R.S.
Vol. I. Buds and Twigs. Vol. II. Leaves. Vol. III. Flowers and
Inflorescences. Vol. IV. Fruits. Vol. V. Form and Habit, with an
Appendix on Seedlings. Crown 8vo. With numerous illustrations.
41. ^d, net each. Price for the set of five volumes, 20s, net.

Nature, The clear and simple way in which the author treats the
subject is sure to inspire many with interest and enthusiasm for the
study of forest botany.... The work will be found indispensable to those
students who wish to make an expert study of forest botany. At the same
time it is expressed in language so clear and devoid of technicalities that
the amateur who wishes to know something about our trees and shrubs will
find this one of the most useful guides to which he can turn. ...The work is
a many sided one, acting not oi3y as a guide to the naturalist in the field,
but also as a laboratory handbook, where the use of the lens and
microscope may be employed to amplify the study of objects already
observed in their natural habitats. Botanists generally, and especially
forest botanists will welcome the appearance of this book as supplying
a decided want, and filling a distinct gap in our literature of forest
botany.

Grasses : a Handbook for use in the Field and Laboratory.
By H. Marshall Ward, ScD., F.R.S. Crown 8vo. With
81 figures. 6s,

Field, The work is essentially suited to the requirements of those
desirous of studying the grasses commonly grown in this country, and
it can fairly be said that it furnishes an amount of information seldom
obtained in more pretentious volumes.

P. T. O.

Cambridge Biological Series
A Treatise on the British Freshwater Algse. By

G. S. West, M.A., A.R.C.S., F.L.S., Lecturer in Botany in the

University of Birmingham. Demy 8vo. With a frontispiece and

1 66 illustrations. lor. 6^. neU

Nature » Its aim is stated as ''to give the student a concise account

of the structure, habits and life-histories of Freshwater Algae, and also

to enable him to place within the prescribed limits of a genus any Alg^

he may find in the freshwater of the British Islands.** To do this within

the limits of an octavo volume of less than 400 pages, in which are

numerous illustrations, is a task possible of accomplishment only by one

very familiar with the subject and skilled in concise expression; but that

it has been successfully done will, we think, be the verdict after testing the

book thoroughly.... Prof. West's treatment of his subject is instructive and

stimulating.

A Manual and Dictionary of the Flowering Plants
and Ferns. By J. C. Willis, M.A., Sc.D., Director of the Royal
Botanic Gardens, Ceylon. Third edition* Crown 8vo. lof . 6t/.

Field, Taking this handy volume and a local flora, the traveller or
student may do an enormous amount of practical field work without any
other botanical literature whatever.... The result is a work that ought to be
included in every library of botany and horticulture or agriculture, and it is
certainly one that the nomadic botanist cannot afford to leave at home....
We have used the original edition of this work since its publication, and
have found it to be one of the most useful and comprehensive works on
plants ever produced.

Aihenaum, The whole is well abreast of modem research, and a
thoroughly business-like volume, lucid though compact.

Agriculture in the Tropics. An elementary Treatise,
~ C. Willis, M.A., Sc.D. Demy 8vo. With 25 plates.

net.

*js. 6d.

Palseontology — Invertebrate. By Henry Woods, M.A.,

F.G.S., University Lecturer in Palaeozoology. Fourth edition. Crown
8vo. With 151 illustrations. 6s,

Outlines of Vertebrate Palaeontology for students
of Zoology. By Arthur Smith Woodward, M.A., F.R.S.,
Keeper of the Department of Geology in the British Museum. Demy
8vo. With 228 illustrations. 14J.

Athenaum, The author is to be congratulated on having produced a
work of exceptional value, dealing with a difficult subject in a thoroughly
sound manner.

CAMBRIDGE UNIVERSITY PRESS
ILonJon: FETTER LANE, E.C.

C. F. CLAY, Manager

ffitlttOrargfj: 100, PRINCES STREET

ALSO

iontJon: H. K. LEWIS, 136, GOWER STREET, W.C.

c

COUNTWAY UBRASY

HC 2EMX ♦